Publications of Prof. Dr. Wim Ubachs

Submitted



J.W.F. van Hofslot, I.E. Thompson, A. Touwen, N. Balasubramanian, R. Bause, H.L. Bethlem, A. Borschevsky, T.H. Fikkers, S. Hoekstra, S.A. Jones, J.E.J. Levenga, M.C. Mooij, H. Mulder, Bastiaan A. Nijman, E.H. Prinsen, B.J. Schellenberg, L. van Sloten, R.G.E. Timmermans, W. Ubachs, J. de Vries, L. Willmann (for the NL-eEDM collaboration)
2D transverse laser cooling of a hexapole focused beam of cold BaF molecules
Submitted (2025); arXiv version

A. Altman, R. Tobias, A.S. Bogomolov, M.L. Diouf, F.M.J. Cozijn, A.G. Csaszar, C. Lauzin, W. Ubachs
Precise frequencies of H₂¹⁶O lines protected for radio astronomy
Submitted (2025)

I.I. Agafonova, G. Yu. Golubiatnikov, Y. Gong, C. Henkel, K.-T. Kim, M.G. Kozlov, A.V. Lapinov, S.A. Levshakov, K.M. Menten, W. Ubachs, W. Yang
Detection of a reduced electron-to-proton mass ratio in the Galactic low-density environment
Submitted (2025)

D.J. Engels, H.K. Schubert, M. Kharbedia, W. Ubachs, O.O. Versolato,
Spectroscopic Imaging of Tin Vapor Near Plasma Threshold
Accepted Phys. Rev. Research (2025)

Published



E.J. Salumbides, Y. Ezzo, Z. Mazzotta, W. Ubachs, K.S.E. Eikema, O. Versolato, S. Witte
Arbitrary pulse shaping in a mid-infrared optical parametric oscillator source
Optics Express 33, 20656-20663 (2025)

K.-F. Lai, W. Ubachs, M. Beyer
Precision measurement of the last bound states in H₂ and determination of the H + H scattering length
Phys. Rev. A 111, 022803 (2025); arXiv version

M.C. Mooij, H.L. Bethlem, A. Boeschoten, A. Borschevsky, T.H. Fikkers, S. Hoekstra, J.W.F. van Hofslot, K. Jungmann, V.R. Marshall, T.B. Meijknecht, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann
A novel method to determine the phase-space distribution of a pulsed molecular beam
J. Phys. B 58, 015303 (2025); arXiv version

V. Hermann, B. Rothmund, F.M.J. Cozijn, M.L. Diouf, W. Ubachs, M. Schloesser
Pressure control of tritiated hydrogen isotopologues in hermetically sealed vessels by non-evaporable getters for sub-Doppler-resolution spectroscopy
Vacuum 230, 113708 (2024)

I.I. Agafonova, O.S. Bayandina, Y. Gong, C. Henkel, K.-T. Kim, M.G. Kozlov, B. Lankhaar, S.A. Levshakov, K.M. Menten, W. Ubachs, I.E. Val'tts, W. Yang
Hyperfine structure of the methanol molecule as traced by Class I methanol masers
Mon. Not. Roy. Astron. Soc. 533, 1714 (2024); arXiv version

W. Ubachs, A. Csaszar, M.L. Diouf, F.M.J. Cozijn, R. Tobias
A network approach for the accurate characterization of water lines observable in astronomical masers and extragalactic environments
ACS Earth and Space Chemistry 8, 1901-1912 (2024)
Supporting Information

A. Touwen, J.W.F van Hofslot, T. Qualm, R. Borchers, R. Bause, H.L Bethlem, A. Boeschoten, A. Borschevsky, T.H. Fikkers, S. Hoekstra, K. Jungmann, V.R. Marshall, T.B. Meijknecht, M.C Mooij, R.G.E Timmermans, W. Ubachs, L. Willmann
Manipulating a beam of barium fluoride molecules using an electrostatic hexapole
New J. Phys. 26, 073054 (2024); arXiv version

A. Boeschoten, V.R. Marshall, T.B. Meijknecht, A. Touwen, H.L. Bethlem, A. Borschevsky, S. Hoekstra, J.W.F. van Hofslot, K. Jungmann, M.C. Mooij, R.G.E. Timmermans, W. Ubachs, L. Willmann,
Novel spin-precession method for sensitive EDM searches
Phys. Rev. A 110, L010801 (2024); arXiv version

L. Gianfrani, S.-M. Hu, W. Ubachs
Advances in cavity-enhanced methods for high precision molecular spectroscopy and test of fundamental physics
La Rivista del Nuovo Cimento 47, 229-298 (2024)

M.C Mooij, H.L Bethlem, A. Boeschoten, A. Borschevsky, K. Esajas, T.H. Fikkers, S. Hoekstra, J.W.F van Hofslot, K. Jungmann, V.R. Marshall, T.B. Meijknecht, R.G.E Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin
Influence of source parameters on the longitudinal phase-space distribution of a pulsed cryogenic beam of barium fluoride molecules
New J. Phys. 26, 053009 (2024); arXiv version

F.M.J. Cozijn, M.L. Diouf, W. Ubachs, V. Hermann, M. Schloesser
Precision Measurement of Vibrational Quanta in Tritium Hydride
Phys. Rev. Lett. 132, 113002 (2024); arXiv version

M.I. Malicka, R.W. Field, S. Ryzner, A. Stasik, W. Ubachs, A.N. Heays, N. de Oliveira, W. Szajna, R. Hakalla
FT-spectroscopy of the ¹²C¹⁸O rare isotopologue and deperturbation analysis of the A¹P(v = 3) level
Spectrochim. Acta Part A: Mol. Biomol. Spectr. 312, 124011, (2024)

R. Tobias, M.L. Diouf, F.M.J. Cozijn, W. Ubachs, A. Csaszar
All paths lead to hubs in the spectroscopic networks of water isotopologues H₂¹⁶O and H₂¹⁸O
Supplementary Material
Commun. Chem. 7, 34 (2024)

M.L. Diouf, F.M.J. Cozijn, W. Ubachs
Hyperfine structure in a vibrational quadrupole transition of ortho-H₂
Mol. Phys. 122, e2304101 (2024)

D.J. Engels, R.A. Meijer, H.K. Schubert, W.J. van der Zande, W. Ubachs, O.O. Versolato,
High-resolution spectroscopic imaging of atoms and nanoparticles in thin film vaporization
Appl. Phys. Lett. 123, 254102 (2023); Erratum

Y. Mostafa, L. Behnke, D.J. Engels, Z. Bouza, J. Sheil, W. Ubachs, O.O. Versolato
Production of 13.5 nm light with 5% conversion efficiency from 2 mum laser driven tin microdroplet plasma
Appl. Phys. Lett. 123, 234101 (2023)

N. Hoelsch, I. Doran, F. Merkt, J. Hussels, C.-F. Cheng, E. J. Salumbides, H. L. Bethlem, K. S. E. Eikema, M. Beyer, W. Ubachs, Ch. Jungen
Ionization and dissociation energies of HD and dipole-induced g/u-symmetry breaking
Phys. Rev. A 108, 022811 (2023)

F.M.J. Cozijn, M.L. Diouf, W. Ubachs
Lamb dip of a quadrupole transition in H₂
Phys. Rev. Lett. 131, 073001 (2023); arXiv version

Y. Mostafa, Z. Bouza, J. Byers, I. Babenko, W. Ubachs, O.O. Versolato, M. Bayraktar
Extreme ultraviolet broadband imaging spectrometer using dispersion-matched zone plates
Opt. Lett. 48, 4316-4319 (2023)

L. Behnke, E.J. Salumbides, G. Goeritz, Y. Mostafa, D. Engels, W. Ubachs, O. Versolato
High-energy parametric oscillator and amplifier pulsed light source at 2-mum
Optics Express 31, 24142-24156 (2023)

K.-F. Lai, M. Beyer, W. Ubachs
Spectroscopic study of the F¹S_g⁺ outer well state in H₂, HD and D₂
J. Mol. Spectr. 393, 111778 (2023); arXiv version

M.L. Diouf, R. Tobias, F.M.J. Cozijn, E.J. Salumbides, C. Fabri, C. Puzzarini, A.G. Csaszar, W. Ubachs
Parity-pair-mixing effects in nonlinear spectroscopy of HDO
Optics Express 30, 46040-46059 (2022); Supplementary Material; Dataset 1; Dataset 2;

F.M.J. Cozijn, M.L. Diouf, W. Ubachs
Saturation spectroscopy of R(0), R(2) and P(2) lines in the (2-0) band of HD
Eur. J. Phys. D 76, 220 (2022)

L. Behnke, Y. Mostafa, Z. Bouza, A. Lassise, L. Poirier, J. Sheil, W. Ubachs, O. Versolato
Two-micrometer-wavelength laser-produced tin plasma EUV sources
in International Conference on Extreme Ultraviolet Lithography 2022, SPIE Vol. 12292, 122920T (2022). https://doi.org/10.1117/12.2642234

K. Liang, J. Xu, Y. Wang, H.-F. Lu, W. Ubachs
Gruneisen approach for Universal Scaling of the Brillouin Shift in Gases
New. J. Phys. 24, (2022) 103005

M.L. Diouf, R. Tobias, T.S. van der Schaaf, F.M.J. Cozijn, E.J. Salumbides, A.G. Csaszar, W. Ubachs
Ultraprecise relative energies in the (2, 0, 0) vibrational band of H₂¹⁶O
Mol. Phys. 120 (15-16), e2050430 (2022); Supplementary Material

K.-F. Lai, E.J. Salumbides, M. Beyer, W. Ubachs
Precision measurement of quasi-bound resonances in H₂ and the H + H scattering length
Mol. Phys. 120 (19-20) e2018063 (2022); arXiv version

F.M.J. Cozijn, M.L. Diouf, V. Hermann, E.J. Salumbides, M. Schloesser, W. Ubachs,
Rotational level spacings in HD from vibrational saturation spectroscopy
Phys. Rev. A 105, 062823 (2022); arXiv version

K.-F. Lai, D. Manalili, W. Ubachs, R. Cooke, M. Pettini, N. de Oliveira, E.J. Salumbides
Vacuum UV Fourier-transform spectroscopy of ¹⁶O and ¹⁸O
Astroph. J. Suppl. Series 260, 37 (2022)

M. Denis, P.A.B. Haase, M.C. Mooij, Y. Chamorro, P. Aggarwal, H.L.Bethlem, A. Boeschoten, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, J.W.F. van Hofslot, V.R. Marshall, T.B. Meijknecht, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin
Benchmarking of the Fock space coupled cluster method and uncertainty estimation:
Magnetic hyperfine interaction in the excited state of BaF
Phys. Rev. A 105, 052811 (2022); arXiv version

S. Ryzner, M. I. Malicka, A.N. Heays, R.W. Field, N. de Oliveira, W. Szajna, W. Ubachs, R. Hakalla
VUV-VIS FT spectroscopy of the ¹³C¹⁸O less abundant isotopologue of carbon monoxide:
Analysis of the A¹P(v = 1) multiply-perturbed level
Spectrochimia Acta A 279, 121367 (2022); Supplementary Material

O.O. Versolato, J. Sheil, S.M. Witte, W. Ubachs, R. Hoekstra
Microdroplet-tin plasma sources of EUV radiation driven by solid-state-lasers
J. of Optics 24, 054014 (2022)

J. Hussels, N. Hoelsch, C.-F. Cheng, E. J. Salumbides, H. L. Bethlem, K. S. E. Eikema, Ch. Jungen, M. Beyer, F. Merkt, W. Ubachs
Improved Ionization and Dissociation Energies of the Deuterium Molecule
Phys. Rev. A 105, 022820 (2022); arXiv version

L. Poirier, A. Bayerle, A. Lassise, F. Torretti, R. Schupp, L. Behnke, Y. Mostafa, W. Ubachs, O. Versolato, R. Hoekstra
Absolute cross-calibration of a combined electrostatic and time-of-flight analyzer for energy- and charge-state-resolved spectrometry of tin laser-produced plasma
Appl. Phys. B 128, 39 (2022)

J. Sheil, D.J. Hemminga, M.M. Basko, W. Ubachs, R. Hoekstra, A.J. Neukirch, J. Colgan, and O.O. Versolato
Recent Advances in Modeling Laser-Driven EUV Light Source Plasmas for Nanolithography
In: Optica High-brightness Sources and Light-driven Interactions Congress 2022, Technical Digest Series (Optica Publishing Group, 2022), paper ETh5A.5

O.O. Versolato, R. Schupp, L. Behnke, Y.Y. Mostafa, Z. Bouza, A. Lassise, M. Bayraktar, J. Sheil, R. Hoekstra, W. Ubachs
Solid-state-laser driven plasma produced from laser-preformed tin microdroplets for high-brightness EUV
in Optica High-brightness Sources and Light-driven Interactions Congress 2022, Technical Digest Series (Optica Publishing Group, 2022), paper ETh5A.7

L. Behnke, R. Schupp, Z. Bouza, J. Scheers, J. Sheil, R. Hoekstra, W. Ubachs, and O.O. Versolato
Solid-State-Laser-Produced Microdroplet-Tin Plasma Sources of Extreme Ultraviolet Radiation
in Optica High-brightness Sources and Light-driven Interactions Congress 2022, Technical Digest Series (Optica Publishing Group, 2022), paper EF2A.2

K.-F. Lai, E.J. Salumbides, W. Ubachs, M. Beyer
Shape resonances in H₂ as photolysis reaction intermediates
Phys. Rev. Lett. 127, 183001 (2021); arXiv version

Z. Bouza, J. Byers, J. Scheers, R. Schupp, Y. Mostafa, L. Behnke, Z. Mazzotta, J. Sheil, W. Ubachs, R. Hoekstra, M. Bayraktar, O.O. Versolato
The spectrum of a 1-mum-wavelength-driven tin microdroplet laser-produced plasma source in the 5.5-265.5 nm wavelength range
AIP Advances 11, 125003 (2021)

P. Aggarwal, Y. Yin, K. Esajas, H.L. Bethlem, A. Boeschoten, A. Borschevsky, S. Hoekstra, K. Jungmann, V.R. Marshall, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann
Deceleration and trapping of SrF molecules
Phys. Rev. Lett. 127, 173201 (2021); arXiv version
Physics Synopsis

D. Hemminga, L. Poirier, M.M. Basko, R. Hoekstra, W. Ubachs, O.O. Versolato, J. Sheil
High-energy ions from Nd:YAG laser ablation of tin microdroplets:
Comparison between experiment and a single-fluid hydrodynamic model
Plasma Sources Science Techn. 30, 105006 (2021)

M. Melosso, M.L. Diouf, L. Bizzocchi, M. Harding, F.M.J. Cozijn, C. Puzzarini, W. Ubachs
Hyperfine-Resolved Near-Infrared Spectra of H₂¹⁷O
J. Phys. Chem. A 125, 7884-7890(2021)

M. I. Malicka, S. Ryzner, A.N. Heays, N. de Oliveira, R.W. Field; W. Ubachs, R. Hakalla
Deperturbation analysis of the A¹P(v = 2) level in the ¹²C¹⁸O isotopologue
J. Quant. Spectr. Rad. Transfer 273, 107837 (2021)

P.A.B. Haase, D.J. Doeglas, A. Boeschoten, E. Eliav, M. Ilias, P. Aggarwal, H.L. Bethlem, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, V.R. Marshall, Th. Meijknecht, M. Mooij, K. Steinebach, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin
Systematic study and uncertainty evaluation of P,T-odd relativistic enhancement factors in BaF
J. Chem. Phys. 155, 034309 (2021); arXiv version

M. Germann, S. Patra, J.-Ph. Karr, L. Hilico, V. I. Korobov, E. J. Salumbides, K. S. E. Eikema, W. Ubachs, and J. C. J. Koelemeij
Three-body QED test and fifth-force constraint from vibrations and rotations of HD⁺
Phys. Rev. Res. 3, L022028 (2021)

R. Schupp, L. Behnke, Z. Bouza, Z. Mazzotta, Y. Mostafa, A. Lassise, L. Poirier, M. Bayraktar, J. Sheil, W. Ubachs, R. Hoekstra, O.O. Versolato
Characterization of angularly resolved EUV emission from 2-mum-wavelength laser-driven Sn plasmas using preformed liquid disk targets
J. Phys. D: Applied Physics 54, 365103 (2021); arXiv version

S. Muller, W. Ubachs, K.M. Menten, C. Henkel, N. Kanekar
A study of submillimeter methanol absorption toward PKS1830; Excitation, invariance of the proton-electron mass ratio, and systematics
Astron. Astroph. 652, A5 (2021); arXiv version;

M.L. Diouf, R. Tobias, I. Simko, F.M.J. Cozijn, E.J. Salumbides, W. Ubachs, A. Csaszar
Network-based design of near-infrared Lamb-dip experiments and determination of pure rotational energies of H₂¹⁸O at kHz accuracy
J. Phys. Chem. Ref. Data 50, 023106 (2021); Supplemental: Table 1, Table 2, Table 3, Table 4, Table 5, Table 6, Table 7, Table 8, Table 9

R. Schupp, L. Behnke, J. Sheil, Z. Bouza, W. Ubachs, R. Hoekstra, O.O. Versolato
Characterization of 1- and 2-mum-wavelength laser-produced microdroplet-tin plasma for generating extreme-ultraviolet light
Phys. Rev. Res. 3, 013294 (2021); arXiv version

P. Aggarwal, H.L. Bethlem, A. Boeschoten, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, K. Jungmann, V.R. Marshall, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, S.M. Vermeulen, L. Willmann, Y. Yin, A. Zapara
A supersonic laser ablation beam source with narrow velocity spreads
Rev. Scient. Instrum. 92, 033202 (2021)

K.-F. Lai, M. Beyer, E.J.Salumbides, W. Ubachs
Photolysis production and spectroscopic investigation of the highest vibrational states in H₂ (X¹S_g⁺ v=13,14)
J. Phys. Chem. A 125, 1221-1228 (2021); arXiv version

L. Behnke, R. Schupp, Z. Bouza, M. Bayraktar, Z. Mazzotta, R. Meijer, J. Sheil, S. Witte, W. Ubachs, R. Hoekstra, O. Versolato
Extreme ultraviolet light from a tin plasma driven by a 2-micron-wavelength laser
Optics. Express 29, 4475-4487 (2021)

Y. Wang, Z. Gu, K. Liang, W. Ubachs
Rayleigh-Brillouin light scattering spectroscopy of air; experiment, predictive model and dimensionsless scaling
Mol. Phys. 119, e1804635 (2021); Supplementary Material; arXiv version

Y. Wang, W. Ubachs, C.A.M. de Moraes, W. Marques Jr
Rayleigh-Brillouin scattering in binary mixtures of disparate-mass constituents: SF₆-He, SF₆-D₂ and SF₆-H₂
Phys. Rev. E 103, 013102 (2021); arXiv version

W. Ubachs
Crisis and Catharsis in atomic physics
Science 370, 6520 (2020); arXiv version

J. Hussels, C. Cheng, E.J. Salumbides, W. Ubachs
Chirp-compensated pulsed Titanium-Sapphire laser system for precision spectroscopy
Optics Letters 45, 5909 (2020); arXiv version

Sayan Patra, M. Germann, J.-Ph. Karr, M. Haidar, L. Hilico, V.I. Korobov, F.M.J. Cozijn, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij
Proton-Electron Mass Ratio from Laser Spectroscopy of HD⁺ at the Part-Per-Trillion Level
Science 369, 1238-1241 (2020); arXiv version
Perspective on this work

K.F. Lai, W. Ubachs, N. de Oliveira, E.J. Salumbides,
Fourier-transform VUV spectroscopy of ^14,15N and ^12,13C
Atoms 8, 62 (2020); arXiv version

L. Wu, Q. Li, H. Liu, W. Ubachs
Extraction of the translational Eucken factor from light scattering by molecular gas
J. Fluid. Mechanics 901, A23 (2020); arXiv version

M. I. Malicka, S. Ryzner, A.N. Heays, N. de Oliveira, R.W. Field, W. Ubachs, R. Hakalla
High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A¹P (v = 1) level in ¹²C¹⁸O
J. Quant. Spectr. Rad. Transfer 255, 107243 (2020)

Z. Bouza, J. Scheers, A. Ryabtsev, R. Schupp, L. Behnke, C. Shah, J. Sheil, M. Bayraktar, J.R. Crespo Lopez-Urrutia, W. Ubachs, R. Hoekstra, O.O. Versolato
EUV spectroscopy of Sn⁵⁺ - Sn¹⁰⁺ ions in an electron beam ion trap and laser-produced plasmas
J. Phys. B 53, 195001 (2020)

J. Scheers, R. Schupp, R. Meijer, W. Ubachs, R. Hoekstra, O. O. Versolato
Time- and space-resolved optical Stark spectroscopy in the afterglow of laser-produced tin-droplet plasma
Phys. Rev. E 102, 013204 (2020)

K.F. Lai, E.J. Salumbides, W. Ubachs
Two-photon Doppler-free ultraviolet laser spectroscopy on sulphur atoms
J. Phys. B 53, 175002 (2020); arXiv version

O. Versolato, A. Bayerle, M. Bayraktar, L. Behnke, H. Bekker, Z. Bouza, J. Colgan, J.R. Crespo Lopez-Urrutia, M.J. Deuzeman, R. Hoekstra, D. Kurilovich, B. Liu, R. Meijer, A. Neukirch, L. Poirier, S. Rai, A. Ryabtsev, J. Scheers, R. Schupp, J. Sheil, F. Torretti, W. Ubachs, S. Witte
Spectroscopic investigations of YAG-laser-driven microdroplet-tin plasma sources of extreme ultraviolet radiation for nanolithography
J. Phys. Conf. Series 1412, 192006 (2020)

J. Scheers, C. Shah, A. Ryabtsev, H. Bekker, F. Torretti, J. Sheil, D. A. Czapski, J. Berengut, W. Ubachs, J. R. Crespo Lopez-Urrutia, R. Hoekstra, O. O. Versolato
EUV spectroscopy of highly-charged Sn¹³⁺ - Sn¹⁵⁺ ions in an electron beam ion trap
Phys. Rev. A 101, 062511 (2020)

M.L. Diouf, F.M.J. Cozijn, K.F. Lai, E.J. Salumbides, W. Ubachs,
Lamb-peak spectrum of the HD (2-0) P(1) line
Phys. Rev. Res 2, 023209 (2020); arXiv version

F. Torretti, J. Sheil, R. Schupp, M.M. Basko, M. Bayraktar, R.A. Meijer, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato, A.J. Neukirch, J. Colgan
Prominent radiative contributions from multiply-excited states in laser-produced tin plasma for nanolithography
Nature Comm. 11, 2334 (2020)

K.F. Lai, V. Hermann, T.M. Trivikram, M.L. Diouf, M. Schloesser, W. Ubachs, E.J. Salumbides
Precision measurement of the fundamental vibrational frequencies of tritium-bearing hydrogen molecules: T₂, DT, HT
Phys. Chem. Chem. Phys. 22, 8973-8987 (2020); arXiv version

R. Tobias, T. Furtenbacher, I. Simko, A.G. Csaszar, M.L. Diouf, F.M.J. Cozijn, J.M.A. Staa, E.J. Salumbides, W. Ubachs
Spectroscopic-network-assisted precision spectroscopy and its application to water
Nature Comm. 11, 1708 (2020); Supplementary Material

F. Torretti, F. Liu, M. Bayraktar, J. Scheers, Z. Bouza, W. Ubachs, R. Hoekstra, O.O. Versolato
Spectral characterization of an industrial EUV light source for nanolithography
J. Phys. D: Appl. Phys. 53, 055204 (2020)

J. Xu, B. Witschas, K. Liang, Y. Wang, W. Ubachs
Characterization of a novel temperature LIDAR receiver by means of laboratory Rayleigh-Brillouin scattering measurements
Eur. Phys. J. Web Conf. 237, 07004 (2020)

A.N. Heays, B.R. Lewis, N. de Oliveira, W. Ubachs
The spin-forbidden vacuum-ultraviolet absorption spectrum of ¹⁴N¹⁵N
J. Chem. Phys. 151, 224305 (2019); arXiv version

K.-F. Lai, P. Czachorowski, M. Schloesser, M. Puchalski, J. Komasa, K. Pachucki, W. Ubachs, E. J. Salumbides
Precision tests of nonadiabatic perturbation theory with measurements on the DT molecule
Phys. Rev. Res. 1, 033124 (2019)

P. Aggarwal, V.R. Marshall, H.L. Bethlem, A. Boeschoten, A. Borschevsky, M. Denis, K. Esajas, Y. Hao, S. Hoekstra, K. Jungmann, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, S.M. Vermeulen, L. Willmann, Y. Yin, A. Zapara
Lifetime Measurements of the A²P_1/2 and A²P_3/2 States in BaF
Phys. Rev. A 100, 052503 (2019); arXiv version

M. Beyer, N. Holsch, J. Hussels, C.-F. Cheng, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, C. Jungen, F. Merkt
Determination of the interval between the ground states of para- and ortho-H₂
Phys. Rev. Lett. 123, 163002 (2019)

M.L. Diouf, F.M.J. Cozijn, B. Darquie, E.J. Salumbides, W. Ubachs
Lamb-dips and Lamb-peaks in the saturation spectrum of HD
Opt. Lett. 44, 4733 (2019); arXiv version

R. Schupp, F. Torretti, R. Meijer, M. Baryaktar, J. Sheil, J. Scheers, D. Kurilovich, A. Bayerle, A. Schafgans, M. Purvis, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato
Radiation transport and scaling of optical depth in Nd:YAG laser-produced microdroplet-tin plasma
Appl. Phys. Lett. 115, 124101 (2019)

S.H. Jamali, M. de Groen, O.A. Moultos, R. Hartkamp, Th.J.H. Vlugt, W. Ubachs, W. van de Water
Rayleigh-Brillouin light scattering spectra of CO₂ from molecular dynamics
J. Chem. Phys. 151, 064201 (2019)

Y. Hao, L.F. Pasteka, L. Visscher, and the NL-eEDM collaboration: P. Aggarwal, H.L. Bethlem, A. Boeschoten, A. Borschevsky, M. Denis, K. Esajas, S. Hoekstra, K. Jungmann, V.R. Marshall, Th.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin, A. Zapara
High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling
J. Chem. Phys. 151, 034302 (2019); arXiv version

R. Schupp, F. Torretti, R. Meijer, M. Bayraktar, J. Scheers, D. Kurilovich, A. Bayerle, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato
Efficient generation of extreme ultraviolet light from Nd:YAG-driven microdroplet-tin plasma
Phys. Rev. Appl. 12, 014010 (2019)

C. Medcraft, H. Linnartz, W. Ubachs
Cavity Ring-down UV spectroscopy of the C²S⁺-X²P electronic transition of CH
J. Mol. Spectr. 360, 15-23 (2019); arXiv version
Suplementary Material (pgopher files): CH (0,0) band; CH (1,1) band; CH (2,2) band

Y. Wang, W. Ubachs, W. van de Water
Bulk viscosity of CO₂ from Rayleigh-Brillouin light scattering spectroscopy at 532 nm
J. Chem. Phys. 150, 154502 (2019); arXiv version

M.T. Trivikram, E.J. Salumbides, C. Jungen, W. Ubachs
Excitation of H₂ at large internuclear separation: F ¹S_g⁺ outer well states and continuum resonances
Mol. Phys. 117, 2961-2971 (2019)

N. Hoelsch, M. Beyer, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, C. Jungen, F. Merkt
Benchmarking theory with an improved measurement of the ionization and dissociation energies of H₂
Phys. Rev. Lett. 122, 103002 (2019); arXiv version

W. Ubachs, E.J. Salumbides, M.T. Murphy, H. Abgrall, E. Roueff
H₂/HD molecular data for analysis of quasar spectra in search of varying constants
Astron. Astroph. 622, A127 (2019); arXiv version

R. Hakalla, T.M. Trivikram, A.N. Heays, E.J. Salumbides, N. de Oliveira, R.W. Field, W. Ubachs
Precision spectroscopy and comprehensive analysis of perturbations in the A¹P(v = 0) state of ¹³C¹⁸O
Mol. Phys. 117, 79-96 (2019); arXiv version

C. Roth, L.S. Dreissen, E.L. Grundeman, J.J. Krauth, M. Favier, E.J. Salumbides, W. Ubachs, K.S.E. Eikema
Tests of fundamental physics using Ramsey-comb spectroscopy on the hydrogen molecule
Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019

L.S. Dreissen, H.F. Schouten, W. Ubachs, S.B. Raghunathan, T.D. Visser,
Active Two-dimensional Steering of Radiation from a Nano-Aperture
Nano Letters 18, 7207-7210 (2018); arXiv version

J. Scheers, R. Ryabtsev, A. Borschevsky, J.C. Berengut, K. Haris, R. Schupp, D. Kurilovich, F. Torretti, A. Bayerle, E. Eliav, W. Ubachs, O.O. Versolato, R. Hoekstra
Energy level structure of Sn³⁺ ions
Phys. Rev. A98, 062503 (2018); arXiv version

P. Aggarwal, H.L. Bethlem, A. Borschevsky, M. Denis, K. Esajas, P.A.B. Haase, Y. Hao, S. Hoekstra, K. Jungmann, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, W. Ubachs, L. Willmann, A. Zapara
Measuring the electric dipole moment of the electron in BaF
Eur. J. Phys. D 72, 197 (2018); arXiv version

D. Kurilovich, T. de Faria Pinto, F. Torretti, R. Schupp, J. Scheers, A.S. Stodolna, H. Gelderblom, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato
Expansion Dynamics After Laser-Induced Cavitation in Liquid Tin Microdroplets
Phys. Rev. Appl. 10, 054005 (2018); arXiv version

C. Cheng, J. Hussels, M. Niu, H.L. Bethlem, K.S.E. Eikema, E.J. Salumbides, W. Ubachs, M. Beyer, N. Hoelsch, J. A. Agner, F. Merkt, L.G. Tao, S.M. Hu, C. Jungen
Dissociation energy of the hydrogen molecule at 10^-9 accuracy
Phys. Rev. Lett. 121, 013001 (2018); arXiv version

M.T. Trivikram, M. Schloesser, W. Ubachs, E.J. Salumbides
Relativistic and QED effects in the fundamental vibration of T₂
Phys. Rev. Lett. 120, 163002 (2018); arXiv version

F.M.J. Cozijn, P. Dupre, E.J. Salumbides, K.S.E. Eikema, W. Ubachs
Sub-Doppler frequency metrology in HD for tests of fundamental physics
Phys. Rev. Lett. 120, 153002 (2018); arXiv version

A. Bayerle, M.J. Deuzeman, S. van der Heijden, D. Kurilovich, T. de Faria Pinto, A. Stodolna, S. Witte, K.S.E. Eikema, W. Ubachs, R. Hoekstra, O.O. Versolato
Sn ion energy distributions of ns- and ps-laser produced plasmas
Plasma Science Sources and Technology 27, 045001 (2018); arXiv version

F. Torretti, R. Schupp, D. Kurilovich, A. Bayerle, J. Scheers, W. Ubachs, R. Hoekstra, O.O. Versolato
Short-wavelength out-of-band EUV emission from Sn laser-produced plasma
J. Phys. B 51, 045005 (2018); arXiv version

R.K. Altmann, L.S. Dreissen, E.J. Salumbides, W. Ubachs, K.S.E. Eikema
Deep-ultraviolet frequency metrology of H₂ for tests of molecular quantum theory
Phys. Rev. Lett. 120, 043204 (2018)

D. Kurilovich, M.M. Basko, D.A. Kim, F. Torretti, R. Schupp, J.C. Visschers, J. Scheers, R. Hoekstra, W. Ubachs, O.O. Versolato
Power-law scaling of plasma pressure on laser-ablated tin microdroplets
Physics of Plasmas 25, 012709 (2018); arXiv version

Y. Wang, K. Liang, W. van de Water, W. Marques Jr, W. Ubachs
Rayleigh-Brillouin light scattering spectroscopy in nitrous oxide (N₂O)
J. Quant. Spectr. Rad. Transfer 206, 63-69 (2018); Supplementary Material; arXiv version

W. Ubachs
Search for varying constants of nature from astronomical observation of molecules
Space Science Reviews 214, 3 (2018); arXiv version

M. Favier, L.S. Dreissen, C.F. Roth, E.L. Gruendeman, J.J. Krauth, E.J. Salumbides, W. Ubachs, R.K. Altmann, K.S.E. Eikema
Precision Spectroscopy in the Deep-UV and Shorter Wavelengths for Tests of Quantum-Electrodynamics and the Proton Radius Puzzle
Conference on Precision Electromagnetic Measurements, Paris (2018)

M. Schloesser, X. Zhao, M.T. Trivikram, W. Ubachs, E.J. Salumbides
CARS spectroscopy on the (v=0-1) band in T₂
J. Phys. B. 50 (2017) 214004; arXiv version

M. Dapra, C. Henkel, S.A. Levshakov, K.M. Menten, S. Muller, H.L. Bethlem, S. Leurini, A.V. Lapinov, W. Ubachs
Testing the variability of the proton-to-electron mass ratio from observations of methanol in the dark cloud core L1498
Mon. Not. Roy. Astron. Soc. 472, 4434-4443 (2017); arXiv version

S. Spieler, M. Kuhn, J. Postler, M. Simpson, R. Wester, P. Scheier, W. Ubachs, X. Bacalla, J. Bouwman, H. Linnartz
C₆₀⁺ and the Diffuse Interstellar Bands: An Independent Laboratory Check
Astroph. J. 846, 168 (2017); arXiv version

T.M. Trivikram, R. Hakalla, A.N. Heays, M.L. Niu, S. Scheidegger, E.J. Salumbides, N. de Oliveira, R.W. Field, W. Ubachs
Perturbations in the A¹P, v=0 state of ¹²C¹⁸O investigated via complementary spectroscopic techniques
Mol. Phys. 115, 3178-3191 (2017); Supplementary Material

M. Glass-Maujean, Ch. Jungen, A.-M. Vasserot, H. Schmoranzer, A. Knie, S. Kuebler, A. Ehresmann, W. Ubachs
Experimental and theoretical studies of the nps ¹S_u⁺ and nppi ¹P_u⁺ (n >= 4, N'=1-6) states of D₂: energies, natural widths, absorption line intensities, and dynamics
J. Mol. Spectr. 338, 22-71 (2017)

F. Torretti, A. Windberger, A. Ryabtsev, S. Dobrodey, H. Bekker, W. Ubachs, R. Hoekstra, E.V. Kahl, J.C. Berengut, J.R. Crespo Lopez-Urrutia, O.O. Versolato
Optical spectroscopy of complex open 4d-shell ions Sn7+ - Sn10+
Phys. Rev. A 95, 042503 (2017); arXiv version

M. Bainbridge, M. Barstow, N. Reindl, L. Tchang-Brillet, T. Ayres, J. Webb, J. Barrow, J. Hu, J. Holberg, S. Preval, W. Ubachs, V. Dzuba, V. Flambaum, V. Dumont, J. Berengut
Probing the gravitational dependence of the fine-structure constant from observations of white dwarf stars
Universe 3, 32 (2017); arXiv version; Cover page journal

M. Dapra, P. Noterdaeme, M. Vonk, M.T. Murphy, W. Ubachs
Analysis of carbon monoxide absorption at z_abs = 2.5 to constrain the variation of the proton-to-electron mass ratio
Month. Not. Royal Astron. Soc. 467 (2017) 3848-3855; arXiv version

M.J. Deuzeman, A.S. Stodolna, E.E.B. Leerssen, A. Antoncecchi, N. Spook, T. Kleijntjens, J. Versluis, S. Witte, K.S.E. Eikema, W.Ubachs, R.Hoekstra, O.O.Versolato
Ion distribution and ablation depth measurements of a fs-ps laser-irradiated solid tin target
J. Appl. Phys. 121 (2017) 103301; arXiv version

Y. Wang, Y. Yu, K. Liang, W. Marques Jr, W. van de Water, W. Ubachs
Rayleigh-Brillouin scattering in SF₆ in the kinetic regime
Chem. Phys. Lett. 669 (2017) 137-142; arXiv version

R. Hakalla, M.L. Niu, R. W. Field, A. Heays, E. Salumbides, G. Stark, J.R. Lyons, M. Eidelsberg, J.L. Lemaire, S.R. Federman, N. de Oliveira, W. Ubachs
Fourier-transform spectroscopy of ¹³C¹⁷O and deperturbation analysis of the A¹Pi (v=0-3) levels
J. Quant. Spectr. Rad. Transfer 189 (2017) 312-328; ; Supplementary Material
arXiv version

M. Dapra, M. van der Laan, M.T. Murphy, W. Ubachs
Constraint on a varying proton-electron mass ratio from H₂ and HD at z_abs=2.34
Month. Not. Roy. Soc. Astr. 465 (2017) 4057-4073; arXiv version

P. Noterdaeme, J.-K. Krogager, S. Balashev, J. Ge, N. Gupta, T. Kruehler, C. Ledoux, M.T. Murphy, I. Paris, P. Petitjean, H. Rahmani, R. Srianand, W. Ubachs
Discovery of a Perseus-like cloud in the early universe;
HI-to-H2 transition, carbon monoxide and small dust grains at z_abs2.65 toward the quasar J0000+0048
Astron. Astroph. 597 (2017) A82; arXiv version

J. Biesheuvel, J.-Ph. Karr, L. Hilico, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij
High-precision spectroscopy of the HD⁺ molecule at the 1-p.p.b. level
Appl. Phys. B 123 (2017) 23; arXiv version

C. Cheng, A.P.P. van der Poel, P. Jansen, M. Quintero-Perez, T.E. Wall, W. Ubachs, H.L. Bethlem
Molecular fountain
Phys. Rev. Lett. 117, 253201 (2016); arXiv version; See also Physics Viewpoint

W. Ubachs
A testing time for antimatter
Science 354, 546-547 (2016); arXiv version

M.T. Trivikram, M. Niu, P. Wcislo, W. Ubachs, E.J. Salumbides
Precision measurements and test of molecular theory in highly-excited vibrational states of H₂(v=11)
Appl. Phys. B 122, 294 (2016); arXiv version

M.L. Niu, R. Hakalla, T. Madhu Trivikram, A.N. Heays, N. de Oliveira, E.J. Salumbides, W. Ubachs
Spectroscopy and perturbation analysis of the A¹Pi(v=0) state of ¹³C¹⁶O
Mol. Phys. 114 (2016) 2857-2867; arXiv version

X. Bacalla, E.J. Salumbides, H. Linnartz, W. Ubachs, D. Zhao
A spectroscopic survey of electronic transitions of C₆H, ¹³C₆H, and C₆D
J. Phys. Chem. A 120, 6401-6417 (2016); arXiv version

W. Ubachs, J. Bagdonaite, E.J. Salumbides, M.T. Murphy, L. Kaper
Search for a drifting proton-electron mass ratio from H₂
Rev. Mod. Phys. 88, 021003 (2016); arXiv version

A. Windberger, F. Torretti, A. Borschevsky, A. Ryabtsev, S. Dobrodey, H. Bekker, E. Eliav, U. Kaldor, W. Ubachs, R. Hoekstra, J.R. Crespo Lopez-Urrutia, O.O. Versolato
Analysis of the fine structure of Sn 11+ ... 14+ ions by optical spectroscopy in an electron beam ion trap
Phys. Rev. A 94, 012506 (2016); arXiv version

D. Kurilovich, A.L. Klein, F. Torretti, A. Lassise, R. Hoekstra, W. Ubachs, H. Gelderblom, O.O. Versolato
Plasma Propulsion of a Metallic Micro-droplet and its Deformation upon Laser Impact
Phys. Rev. Appl. 6, 014018 (2016); arXiv version

M. Dapra, M.L. Niu, E.J. Salumbides, M.T. Murphy, W. Ubachs
Constraint on a cosmological variation in the proton-to-electron mass ratio from electronic CO absorption
Astroph. J. 826, 192 (2016); arXiv version

W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema, E.J. Salumbides
Physics beyond the Standard Model from hydrogen spectroscopy
J. Mol. Spectr. 320 (2016) 1-12; arXiv version

R. Hakalla, M.L. Niu, E.J. Salumbides, A.N. Heays, G. Stark, J.R. Lyons, M. Eidelsberg, J.L. Lemaire, S.R. Federman, M. Zachwieja, W. Szajna, P. Kolek, I. Piotrowska, M. Ostrowska-Kopec, R. Kepa, N. de Oliveira, R.W. Field, W. Ubachs
VIS and VUV spectroscopy of 12C17O and deperturbation analysis of the A1Pi, v = 1-5 levels
Adv. Royal Soc. Chem. 6, 31588-31606 (2016)

M. Glass-Maujean, Ch. Jungen, G. D. Dickenson, N. de Oliveira, W. Ubachs
The excited J=0 ¹S_u⁺ levels of D₂: Measurements and ab initio quantum defect study
J. Mol. Spectr. 320 (2016) 33-38

J. Biesheuvel, J.-Ph. Karr, L. Hilico, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij
Probing QED and fundamental constants through laser spectroscopy of vibrational transitions in HD⁺
Nature Comm. 7, 10385 (2016); arXiv version

M.L. Niu, E.J. Salumbides, A.N. Heays, N. de Oliveira, R.W. Field, W. Ubachs
Spectroscopy and perturbation analysis of the CO A1Pi-X1S+ (2,0), (3,0) and (4,0) bands
Mol. Phys. 114, 627-636 (2016); arXiv version

B. Witschas, O. Reitebuch, C. Lemmerz, P.G. Kableka, S. Kondratyev, Z.Y. Gu, W. Ubachs
The measurement of tropospheric temperature profiles using Rayleigh-Brillouin scattering:
Results from laboratory and atmospheric studies
EPJ Web of Conferences 119, 127004 (2016)

M.L. Niu, E.J. Salumbides, W. Ubachs
Test of quantum chemistry in vibrationally-hot hydrogen molecules
J. Chem. Phys. (Comm) 143, 081102 (2015); arXiv version

M. Dapra, J. Bagdonaite, M.T. Murphy, W. Ubachs
Constraint on a varying proton-to-electron mass ratio from molecular hydrogen absorption toward quasar SDSS J123714.60+064759.5
Month. Not. Royal Astron. Soc. 454, 489-506 (2015); arXiv version

Z. Gu, W. Ubachs, W. Marques Jr, W. van de Water
Rayleigh-Brillouin scattering in binary gas mixtures
Phys. Rev. Lett. 114, 243902 (2015); arXiv version

E.J. Salumbides, A.N. Schellekens, B. Gato-Rivera, W. Ubachs
Constraints on extra dimensions from molecular spectroscopy
New. J. Phys. 17, 033015 (2015); arXiv version

J. Bagdonaite, W. Ubachs, M.T. Murphy, J.B. Whitmore
A constraint on a varying proton-electron mass ratio 1.5 billion years after the Big Bang
Phys. Rev. Lett. 114, 071301 (2015); Supplemental material; arXiv version

M. Glass-Maujean, Ch. Jungen, G. D. Dickenson, W. Ubachs, N. de Oliveira, D. Joyeux, L. Nahon
VUV Fourier-Transform absorption study of the nppi ¹P_u^-, v, N - X¹S_g⁺, v = 0, N, transitions in D₂
J. Mol. Spectr. 315, 147-154 (2015)

M.L. Niu, A.N. Heays, S. Jones, E.J. Salumbides, E.F. van Dishoeck, N. de Oliveira, L. Nahon, W. Ubachs
VUV-synchrotron absorption studies of N₂ and CO at 900 K
J. Mol. Spectr. 315, 137-146 (2015); arXiv version

M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs
The ²P-X²P electronic spectra of long carbon chain ⁽¹³⁾C_2nH/D molecules for (n=4-6)
Mol. Phys. 113, 2063-2072 (2015)

E.J. Salumbides, J. Bagdonaite, H. Abgrall, E. Roueff, W. Ubachs,
H2 Lyman and Werner band lines and their sensitivity for a variation of the proton-electron mass ratio in the gravitational potential of white dwarfs
Month. Not. Roy. Astron. Soc. 450, 1237-1245 (2015); arXiv version
Supplementary Material: Werner Q-lines; Werner PR-lines; Lyman lines

N. Kanekar, W. Ubachs, K.M. Menten, J. Bagdonaite, A. Brunthaler, C. Henkel, S. Muller, H.L. Bethlem, M. Dapra
Constraint on changes in the proton-electron mass ratio using methanol lines
Month. Not. Royal Astron. Soc. Letters 448 , L104-L108 (2015); arXiv version

X. Bacalla, D. Zhao, E.J. Salumbides, M.A. Haddad, H. Linnartz, W. Ubachs
The B²Pi - X²Pi electronic origin band of ¹³C₆H
J. Mol. Spectr. 308-309, 41-44 (2015); arXiv version

M.L. Niu, F. Ramirez, E.J. Salumbides, W. Ubachs
High-precision laser spectroscopy of CO A¹Pi - X¹S⁺(2,0), (3,0) and (4,0) bands
J. Chem. Phys. 142, 044302 (2015); arXiv version

T.J. Pinkert, O. Boll, L. Willmann, G.S.M. Jansen, E.A. Dijck, B. Groeneveld, R. Smets, F.C. Bosveld, W. Ubachs, K. Jungmann, K.S.E. Eikema, J.C.J. Koelemeij
Effect of soil temperature on one-way optical frequency transfer through dense-wavelength-division-multiplexing fibre links
Applied Optics 54, 728-738 (2015); arXiv version

A. Schulz, C. Henkel, K.M. Menten, S. Muller, D. Muders, J. Bagdonaite, W. Ubachs
The inhomogeneous ISM toward PKS 1830–211 SW -
A detailed view on molecular gas at a look-back time of 7.5 Gyr
Astron. Astroph. 574, A108 (2015); arXiv version

M.A. Haddad, D. Zhao, W. Ubachs
Gas-phase electronic absorption spectra of deuterated linear seven-carbon radicals
Spectroscopy Letters 48, 567-571 (2015)

E. J. Salumbides, D. Bailly, M. Vervloet, W. Ubachs
B¹S_u⁺ and EF¹S_g⁺ level energies of D₂
J. Mol. Spectr. 305, 34-39 (2014); arXiv version

J. Bagdonaite, E.J. Salumbides, S.P. Preval, M.A. Barstow, J.D. Barrow, M.T. Murphy, W. Ubachs
Limits on a Gravitational Field Dependence of the Proton-Electron Mass Ratio from H₂ in White Dwarf Stars
Phys. Rev. Lett. 113, 123002 (2014); arXiv version

B. Witschas, Z.Y. Gu, W. Ubachs
Temperature retrieval from Rayleigh-Brillouin scattering profiles measured in air
Optics Express 22, 29655-29667 (2014)

W. Ubachs, E.J. Salumbides, K.S.E. Eikema, N. de Oliveira, L. Nahon
Novel techniques in VUV high-resolution spectroscopy
Journal of Electron Spectroscopy and Related Phenomena 196, 159-164 (2014); arXiv version

Z.Y. Gu, W. Ubachs
A systematic study of Rayleigh-Brillouin scattering in air, N₂ and O₂ gases
J. Chem. Phys. 141, 104320 (2014); arXiv version

Z.Y. Gu, W. Ubachs, W. van de Water
Rayleigh-Brillouin scattering of carbon dioxide
Opt. Lett. 39, 3301 (2014); arXiv version

T. Steimle, W. Ubachs
Introduction to the Special issue Spectroscopic Tests of Fundamental Physics
J. Mol. Spectr. 300, 1-2 (2014)

M. Niu, E.J. Salumbides, G.D. Dickenson, K.S.E. Eikema, W. Ubachs
Precision spectroscopy of the X¹S_g⁺, v=0-1 (J=0-2) rovibrational splittings in H₂, HD and D₂
J. Mol. Spectr. 300, 44-54 (2014); arXiv version

E.J. Salumbides, W. Ubachs, V.I. Korobov
Bounds on fifth forces at the sub-Angstrom length scale
J. Mol. Spectr. 300, 65-69 (2014); arXiv version

A.J. de Nijs, W. Ubachs, H.L. Bethlem
Ramsey type microwave spectroscopy on CO (a³P)
J. Mol. Spectr. 300, 79-85 (2014)

M.R. Schmidt, J. Krelowski, G.A. Galazutdinov, D. Zhao, M.A. Haddad, W. Ubachs, H. Linnartz
Detection of vibronic bands of C₃ in a translucent cloud towards HD 169454
Monthly Not. Roy. Astron. Society 441, 1134-1146 (2014); arXiv version;

M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs
Rotationally resolved spectra of the 4051 A comet band of C₃ for all six ¹²C and ¹³C isotopologues
J. Mol. Spectr. 297, 41-50 (2014)

G.D. Dickenson, W. Ubachs
VUV Spectroscopic Study of the B''B¹S_u⁺ State of H₂
Mol. Phys. 112 (2014) 1089-1093; arXiv version

A. Heays, R. Visser, R. Gredel, W. Ubachs, B.R. Lewis, S.T. Gibson, E.F. van Dishoeck
Isotope selective photodissociation of N₂ by the interstellar radiation field and cosmic rays
Astronomy Astrophysics 562, A61 (2014); arXiv version

Y. Ma, H. Li, Z. Gu, W. Ubachs, Y. Yu, J. Huang, B. Zhou, Y. Wang, K. Liang
Analysis of Rayleigh-Brillouin spectral profiles and Brillouin shifts in nitrogen gas and air
Optics Express 22, 2092-2104 (2014)

J. Bagdonaite, W. Ubachs, M.T. Murphy, J.B. Whitmore
Analysis of Molecular Hydrogen Absorption toward QSO B0642-5038 for a Varying Proton-to-Electron Mass Ratio
Astrophysical Journal 782, 10 (2014); arXiv version

P. Jansen, H.L. Bethlem, W. Ubachs
Perspective: Tipping the scales - search for drifting constants from molecular spectra
J. Chem. Phys. 140, 010901 (2014); arXiv version

Z. Gu, W. Ubachs
Further validation and refinement of the Tenti model for atmospheric LIDAR backscatter
ESA report, 4200021396-CCN2 (2014).

W. Ubachs
Zijn Natuurconstanten Constant ? Diligentialezing 16 Dec. 2013

J. Bagdonaite, M. Dapra, P. Jansen, H.L. Bethlem, W. Ubachs, S. Muller, C. Henkel, K.M. Menten,
Robust constraint on a drifting proton-to-electron mass ratio from methanol observation at three radio telescopes
Phys. Rev. Lett. 111, 231101 (2013); arXiv version
See also: Physics Synopsis

A. de Nijs, D. Zhao, H.L. Bethlem, H. Linnartz, W. Ubachs
Testing the mass-scaling relations in the a³P state of 12C18O and 13C16O
J. Mol. Spectr. 292, 20 (2013)

S.B. Raghunathan, H.F. Schouten, W. Ubachs, B. Ea Kim, C.H. Gan, T.D. Visser
Dynamic beam steering from a sub-wavelength slit by selective excitation of guided modes
Phys. Rev. Lett. 111, 153901 (2013)


A. Walsh, D. Zhao, W. Ubachs, H. Linnartz
Optomechanical shutter modulated broadband cavity-enhanced absorption spectroscopy of molecular transients of astrophysical interest
J. Phys. Chem. A 117, 9363-9369 (2013)


M.L. Niu, E.J. Salumbides, D. Zhao, N. de Oliveira, D. Joyeux, L. Nahon, R.W. Field, W. Ubachs
High resolution spectroscopy and perturbation analysis of the CO A1P-X1S+ (0,0) and (1,0) bands
Mol. Phys. 111, 2163 (2013)

P. Jansen, I. Kleiner, C. Meng, R. Lees, M.H.M. Janssen, W. Ubachs, H.L. Bethlem
Prospects for high-resolution microwave spectroscopy of methanol in a Stark-deflected molecular beam
Mol. Phys. 111, 1923 (2013); arXiv version


X. Li, A. Heays, R. Visser, W. Ubachs, B.R. Lewis, S.T. Gibson, E.F. van Dishoeck
Photodissociation of interstellar N₂
Astronomy and Astrophysics 555, A14 (2013); arXiv version


W. Ubachs, W. Vassen, E.J. Salumbides, K.S.E. Eikema
Precision metrology on the hydrogen atom in search for new physics
Ann. Phys. (Berlin) 575, A113 (2013)

F.M.J. Cozijn, J. Biesheuvel, A.S. Flores, W. Ubachs, G. Blume, A. Wicht, K. Paschke, G. Erbert, J.C.J. Koelemeij
Laser cooling of beryllium ions using a frequency-doubled 626 nm diode laser
Optics Letters 38, 2370 (2013); Paper chosen as Spotlight on optics by the Opt. Soc. of Am.

Z. Gu, B. Witschas, W. van de Water, W. Ubachs
Rayleigh-Brillouin scattering profiles of air at different temperatures and pressures
Appl. Optics 52, 4640 (2013)


E.J. Salumbides, J.C.J. Koelemeij, J. Komasa, K. Pachucki, K.S.E. Eikema, W. Ubachs
Bounds on fifth forces from precision measurements on molecules
Phys. Rev. D87 (2013) 112008; arXiv version


J. Bagdonaite, P. Jansen, C. Henkel, H.L. Bethlem, K.M. Menten, W. Ubachs
A stringent limit on a drifting proton-to-electron mass ratio from alcohol in the early Universe
Science 339, 46 (2013)
Online: Science Express 13 Dec. 2012; DOI 10.1126/science.1224898

G.D. Dickenson, M.L. Niu, E.J. Salumbides, J. Komasa, K.S.E. Eikema, K. Pachucki, W. Ubachs
Fundamental Vibration of Molecular Hydrogen
Phys. Rev. Lett. 110, 193601 (2013); arXiv version

P. Jansen, L.-H. Xu, I. Kleiner, H.L. Bethlem, W. Ubachs
Methyl mercaptan (CH₃SH) as a probe for mu-variation
Phys. Rev. A87, 052509 (2013); arXiv version;

J. Biesheuvel, D.W.E. Noom, E.J. Salumbides, K.T. Sheridan, W. Ubachs, J.C.J. Koelemeij
Widely tunable laser frequency offset lock with 30 GHz range and 5 THz offset
Optics Express 21, 14008-14016 (2013)

Z. Gu, W. Ubachs
Temperature-dependent bulk viscosity of nitrogen gas determined from Rayleigh-Brillouin scattering
Optics Letters 38, 1110 (2013)


W. Ubachs
H₂ as a possible carrier of the DIBs ?
The Diffuse Interstellar bands, IAU Symposium 297 proceedings, 375-377 (2013)


A.J. Walsh, D. Zhao, H. Linnartz, W. Ubachs
Broadband cavity-enhanced absorption spectrocopy; a new approach to search for DIB carriers
The Diffuse Interstellar bands, IAU Symposium 297 proceedings, 281-285 (2013)


M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs
The 4051 A comet band of ¹³C₃
The Diffuse Interstellar bands, IAU Symposium 297 proceedings, 297-299 (2013)


W. Ubachs
Search for drifting constants and fifth forces from precision measurements on molecules
31st SPP Physics Congres Philipines 2013


W. Ubachs
The H₂ molecule; test of QED and varying constants
Frontiers in Optics 2013; Laser Science XXIX, APS/DLS 29th annual meeting, Orlando, Florida

G.D. Dickenson, E.J. Salumbides, M.L. Niu, Ch. Jungen, S.R. Ross, W. Ubachs
Precision spectroscopy of high rotational states in H₂ investigated
by Doppler-free two-photon laser spectroscopy in the EF¹S_g⁺ - X¹S_g⁺ system
Phys. Rev. A 86, 032502 (2012); Supplementary Material


T.J. Pinkert, E.J. Salumbides, M.S. Tahvili, W. Ubachs, E.A.J.M. Bente, K.S.E. Eikema
Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser
Optics Express 20, 21357 (2012)

A.J. de Nijs, W. Ubachs, H.L. Bethlem
Sensitivity of rotational transitions in CH and CD to a possible variation of fundamental constants
Phys. Rev. A86, 032501 (2012)

E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs
The CO A-X system for constraining cosmological drift of the proton-electron mass ratio
Phys. Rev. A86, 022510 (2012)

G.D. Dickenson, W. Ubachs
The D¹P state of HD and the mass scaling relation of its predissociation
J. Phys. B. 45 (2012) 145101
Special mention in Labtalk

J.C.J. Koelemeij, D.W.E. Noom, D. de Jong, M.A. Haddad, W. Ubachs,
Observation of the v = 8 - v = 0 vibrational overtone in cold trapped HD⁺
Appl. Phys. B 107 (2012) 1075-1085

S.B. Raghunathan, C.H. Gan, T. van Dijk, B. Ea. Kim, H.F. Schouten, W. Ubachs, P. Lalanne, T.D. Visser
Plasmon switching: Observation of dynamic surface plasmon steering by selective mode excitation in a sub-wavelength slit
Optics Express 14 (2012) 15326


A. de Lange, G.D. Dickenson, E.J. Salumbides, W. Ubachs, N. de Oliveira, D. Joyeux, L. Nahon
VUV Fourier-transform absorption study of the Lyman and Werner bands in D₂
J. Chem. Phys. 136 (2012) 234310; Supplementary Material

Z. Gu, M.O. Vieitez, E.-J. van Duijn, W. Ubachs
A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths
Rev. Scient. Instrum. 83, 053112 (2012)


M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs
Spin-orbit splitting and lifetime broadening in the A²D state of l-C₅H
Chin. J. Chem. Phys. 25, 129 (2012)


J. Bagdonaite, M.T. Murphy, L. Kaper, W. Ubachs,
Constraint on a variation of the proton-to-electron mass ratio from H₂ absorption towards quasar Q2348-011
Month. Not. Roy. Astron. Soc. 421, 419-425 (2012);

V.V. Ilyushin, P. Jansen, M.G. Kozlov, S.A. Levshakov, I. Kleiner, W. Ubachs, H.L. Bethlem
Sensitivity to a possible variation of the Proton-to-Electron Mass Ratio of Torsion-Wagging-Rotation Transitions in Methylamine (CH₃NH₂)
Phys. Rev. A 85, 032505 (2012); Supplementary material

D. Zhao, H. Linnartz, W. Ubachs
The electronic spectrum of the C_s-C₁₁H₃ radical
J. Chem. Phys. 136, 054307 (2012); Supplementary material

J. Liu, D. Sprecher, F. Merkt, E.J. Salumbides, W. Ubachs
Determination of the ionization and dissociation energies of H2 and He2
AIP. Conf. Proc. 1504, 495 (2012)

H.L. Bethlem, P. Jansen, W. Ubachs
Testing the time-invariance of fundamental constants using cold and not-so-cold molecules
AIP. Conf. Proc. 1504, 454 (2012)

D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema
XUV frequency comb metrology on the ground state of helium
Phys. Rev. A84, 062512 (2011)

A.N. Heays, G. Dickenson, E.J. Salumbides, N. de Oliveira, D. Joyeux, L. Nahon, B.R. Lewis, W. Ubachs,
High-resolution Fourier-transform XUV photoabsorption spectroscopy study of ¹⁴N¹⁵N
J. Chem. Phys. 135, 244301 (2011); Supplementary Material


P. Jansen, I. Kleiner, L.-H. Xu, W. Ubachs, H.L. Bethlem
Sensitivity of transitions in internal rotor molecules to a possible variation of the proton-to-electron mass ratio
Phys. Rev. A 84, 062505 (2011)

G. Dickenson, T. Ivanov, W. Ubachs, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon,
W.U.L. Tchang-Brillet, M. Glass-Maujean, H. Schmoranzer, A. Knie, S. Kubler, A. Ehresmann,
VUV spectroscopic study of the D¹Pi_u state of molecular deuterium
Mol. Phys. 109, 2693-2708 (2011); Supplementary Material
This paper won the 2011 Mol. Phys. Young Authors Prize

A.J. de Nijs, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, H.L. Bethlem
UV frequency metrology on CO (a³P);
Isotope effects and sensitivity to a variation of the proton-to-electron mass ratio
Phys. Rev. A 84, 052509 (2011)

J.A. King, M.T. Murphy, W. Ubachs, J.K. Webb,
New constraint on cosmological variation of the proton-to-electron mass ratio from Q0528-250
Monthly Not. Royal Astron. Soc. 417, 3010-3024 (2011)
Supplementary material

D. Zhao, M.A. Haddad, H. Linnartz, W. Ubachs
C₆H and C₆D: electronic spectra and Renner-Teller analysis
J. Chem. Phys. 135, 044307 (2011)


D. Zhao, M.A. Haddad, H. Linnartz, W. Ubachs
Structure determination of the non-linear hydrocarbon chains C₉H₃ and C₁₁H₃ by deuterium labeling
J. Chem. Phys. 135, 074201 (2011)


E.J. Salumbides, G. Dickenson, T.I. Ivanov, W. Ubachs
QED effects in molecules: test on rotational quantum states of H₂
Phys. Rev. Lett. 107, 043005 (2011)


F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs
First constraint on cosmological variation of the proton-to-electron mass ratio from two independent telescopes
Phys. Rev. Lett. 106, 180802 (2011), Supplementary material.

P. Jansen, L.-H. Xu, I. Kleiner, W. Ubachs, H.L. Bethlem
Methanol as a sensitive probe for spatial and temporal variations of the proton-to-electron mass ratio
Phys. Rev. Lett. 106, 100801 (2011), Supplementary material

D. Sprecher, Ch. Jungen, W. Ubachs, F. Merkt
Towards measuring the ionisation and dissociation energies of molecular hydrogen with sub-MHz accuracy
Faraday Discussions 150, 51-70 (2011)

W. Ubachs, J. Bagdonaite, M.T. Murphy, R. Buning, L. Kaper
Search for cosmological mu variation from high-redshift H₂ absorption; a status report
Astrophys. Space Science (2011); C. Martins and P. Molaro (eds.), From Varying Couplings to Fundamental Physics, p125

T.I. Ivanov, C.A. de Lange, W. Ubachs,
Spectral identification of diffuse resonances in H₂ above the n=2 dissociation limit
J. Chem. Phys. 134, 054309 (2011)


E.J. Salumbides, V. Maslinskas, I.M. Dildar, A.L. Wolf, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs
High precision frequency measurement of the 423 nm Ca I line
Phys. Rev. A83, 012502 (2011)


F. Hamann, N. Kanekar, J.X. Prochaska, M.T. Murphy, S.L. Ellison, A.L. Malec, N. Milutinovic, W. Ubachs,
A high-velocity narrow absorption line outflow in the quasar J212329.6-005052.9
Month. Not. Roy. Astron. Soc. 410, 1957-1974 (2011)


A.L. Wolf, J. Morgenweg, J.C.J. Koelemeij, S.A. van den Berg, W. Ubachs, K.S.E. Eikema
Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped 40Ca⁺ ions
Optics Lett. 36, 49-51 (2011)


D. Zhao, N. Wehres, H. Linnartz, W. Ubachs
Electronic spectra and structure of the non-linear carbon chain C₉H₃
Chem. Phys. Lett. 501, 232-237 (2011)


K.S.E. Eikema, W. Ubachs,
Precision Laser spectroscopy in the Extreme Ultraviolet
Handbook of high resolution spectroscopy, Eds. M. Quack and F. Merkt
John Wiley & Sons, 2010, ISBN: 978-0-470-06653-9, Page 1373-1413

D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema
Extreme ultraviolet frequency comb metrology
Phys. Rev. Lett. 105 (2010) 063001.
See also Physics Synopsis

T. van Dijk, H.F. Schouten, W. Ubachs, T.D. Visser
Observation of linear, nonlinear and singular behavior of the Pancharatnam-Berry phase
SPIE Proceedings (Complex Light and Optical Forces IV Book Series) 7613, 76130E (2010)

G. Dickenson, T. Ivanov, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon,
L. Tchang-Brillet, M. Glass-Maujean, I. Haar, A. Ehresmann, W. Ubachs
Synchrotron VUV radiation studies of the D¹Pi_u state of H₂
J. Chem. Phys. 133, 144317 (2010)


N. Wehres, D. Zhao, W. Ubachs, H. Linnartz
Rotationally resolved A³S_u^-- X³S_u^- spectrum of HC₇H
Chem. Phys. Lett. 497, 30-32 (2010)


M.O. Vieitez, E.-J. van Duijn, W. Ubachs, B. Witschas, A. Meijer, A.S. de Wijn, N. Dam, W. van de Water,
Coherent and spontaneous Rayleigh-Brillouin scattering in molecular gases and gas mixtures
Phys. Rev. A 82, 043836 (2010)


W. Ubachs,
50 jaar Laser (in Dutch)
Ned. Tijdschr. v. Natuurkunde 76 (2010) 172-174.

W. Ubachs,
Maiman gemangeld (in Dutch)
Ned. Tijdschr. v. Natuurkunde 76 (2010) 184-185.

D. Sprecher, J. Liu, Ch. Jungen, W. Ubachs, F. Merkt
Determination of ionization and dissociation energies of HD
J. Chem. Phys. 133, 111102 (2010)
This paper is one of the JCP Editors choice papers of 2010

J. Tumlinson, A.L. Malec, R.F. Carswell, M.T. Murphy, R. Buning, N. Milutinovic, S.L. Ellison, J.X. Prochaska, R.A. Jorgenson, W. Ubachs, A.M. Wolfe
Cosmological concordance or chemical coincidence ?
Deuterated molecular hydrogen abundances at high redshift
Astroph. J. Lett. 718, L156 (2010)


B. Witschas, M.O. Vieitez, E.-J. van Duijn, O. Reitebuch, W. van de Water, W. Ubachs
Spontaneous Rayleigh-Brillouin scattering of ultraviolet light in nitrogen, dry and moist air
Appl. Optics 49 (2010) 4217-4227


J. Liu, D. Sprecher, Ch. Jungen, W. Ubachs, F. Merkt
Determination of ionization and dissociation energies of the deuterium molecule (D₂)
J. Chem. Phys. 132 (2010) 154301


O. Le Rille, A.-G. Straume, O. Vieitez, W. Ubachs, B. Witschas, G.-J. Marseille,
J. de Kloe, A. Stoffelen, K. Houchi, H. Kornich, H. Schyberg
ESA's wind Lidar mission ADM-AEOLUS; on-going scientific activities
related to calibration, retrieval and instrument operation
25th International Lidar Radar Conference Proceedings


T. van Dijk, H.F. Schouten, W. Ubachs, T.D. Visser
The Pancharatnam-Berry phase for non-cyclic polarization changes
Optics Express 18, 10796-10804 (2010)

T.I. Ivanov, G.D. Dickenson, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon, W.U.L. Tchang-Brillet, W. Ubachs,
Fourier-transform spectroscopy of HD in the vacuum ultraviolet at lambda = 87-112 nm
Mol. Phys. 108, 771-786 (2010)

D. Bailly, E.J. Salumbides, M. Vervloet, W. Ubachs,
Accurate level energies in the EF¹S⁺_g, GK¹S⁺_g, H¹S⁺_g, B¹S⁺_u, C¹P_u, B'¹S⁺_u, D¹P_u, I¹P_g, J¹D_g states of H₂
Mol. Phys. 108, 827-846 (2010)
Supplementary Material


A.L. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison,
J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs
Keck telescope constraint on cosmological variation of the proton-to-electron mass ratio
Monthly Not. Royal Astron. Society, 403 (2010) 1541-1555
Additional information: J2123 spectra and Molecular data for hydrogen

C. Gohle, D.Z. Kandula, T. Pinkert, W. Ubachs, K.S.E. Eikema,
XUV frequency comb spectroscopy
Proceedings of the XIX International Conference on Laser Spectroscopy (2009)
Eds: H. Katori, K. Nakagawa, Hitoki Yoneda, World Scientific 2010, p 171-180

L. van der Sneppen, G. Ritchie, G. Hancock, F. Ariese, C. Gooijer, W. Ubachs, R. Haselberg, G.W. Somsen, G.J. de Jong
Evanescent-Wave Cavity Enhanced Spectroscopy as a Tool in Label-Free Biosensing
Conference on Lasers and Electro-Optics: Applications (2010)

D.Z. Kandula, A. Renault, C. Gohle, A.L. Wolf, S. Witte, W. Hogervorst, W. Ubachs, K.S.E. Eikema
Ultrafast double pulse parametric amplification for precision Ramsey metrology
Ultrafast Phenomena XVI. Eds: P. Corkum, S. Silvestri, K.A. Nelson, E. Riedle, R.W. Schoenlein
Springer Series in Chem. Phys. 92, 846-848 (2009)

A.L. Wolf, S.A. Van den Berg, C. Gohle, E.J. Salumbides, W. Ubachs, K.S.E. Eikema
Frequency comb spectroscopy on calcium ions in a linear Paul trap
Ultrafast Phenomena XVI. Eds: P. Corkum, S. Silvestri, K.A. Nelson, E. Riedle, R.W. Schoenlein
Springer Series in Chem. Phys. 92, 852-854 (2009)

W. Ubachs, E.-J. van Duijn, M.O. Vieitez, W. van de Water, N. Dam, J.J. ter Meulen, A.S. Meijer, J. de Kloe, A. Stoffelen, E.A.A. Aben,
A Spontaneous Rayleigh-Brillouin scattering experiment for the characterization of atmospheric Lidar backscatter
ESA report, AO/1-5467/07/NL/HE (2009).


A.L. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison,
J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs
New limit on a varying proton-to-electron mass ratio from high resolution optical quasar spectra
Mem. Soc. Astron. Italiana 80, 882 (2009)


M.O. Vieitez, T.I. Ivanov, E.Reinhold, C.A. de Lange, W. Ubachs,
Spectroscopic observation and characterization of H⁺H^- heavy Rydberg states
J. Phys. Chem. A 113 (2009) 13237-13245


R. Haselberg, L. van der Sneppen, F. Ariese, W. Ubachs, C. Gooijer, G.J. de Jong, G.W. Somsen
Effectiveness of charged non-covalent polymer coatings against protein adsorption to silica surfaces
studied by evanescent-wave cavity ring-down spectroscopy and capillary electrophoresis
Anal. Chem. 81 (2009) 10172-10178


M.J.R. Heck, E. Salumbides, A. Renault, E.A.J.M. Bente, Y.-S. Oei, M.K. Smit, R. Notzel, R. van Veldhoven,
K.S.E. Eikema, W. Ubachs,
Analysis of hybrid mode-locking of two-section quantum dot lasers operating at 1.5 micron
Optics express 17, 18063 (2009)


J. Liu, E.J. Salumbides, U. Hollenstein, J.C.J. Koelemeij, K.S.E. Eikema, W. Ubachs, F. Merkt,
Determination of ionization and dissociation energies of the hydrogen molecule
J. Chem. Phys. 130 (2009) 174306


D. Ityaksov, S. Stolte, H. Linnartz, W. Ubachs,
Rotational analysis of the A²S⁺ (v=1,2) - X²P (v=0) electronic bands of ¹⁵N¹⁸O
J. Mol. Spectr. 255 (2009) 139-143

L. van der Sneppen, F. Ariese, C. Gooijer, W. Ubachs,
Liquid-Phase and Evanescent Wave Ring-Down spectroscopy in analytical chemistry
Annual Review of Analytical Chemistry 2 (2009) 13-35

M.O. Vieitez, T. Ivanov, E. Reinhold, C.A. de Lange, W. Ubachs,
Een Zwaar Bohratoom
Ned. Tijdschr. v. Natuurkunde 75 (2009) 36-38.

L. van der Sneppen, C. Gooijer, W. Ubachs, F. Ariese,
Evanescent Wave Cavity Ring-Down detection of cytochrome c on surface-modified prisms
Sensors and Actuators B 139 (2009) 505-510

A.L. Wolf, S.A. van den Berg, W. Ubachs, K.S.E. Eikema,
Direct frequency comb spectroscopy of trapped ions
Phys. Rev. Lett. 102 (2009) 223901


M.J.R. Heck, A. Renault, E.A.J.M. Bente, Y.-S. Oei, M.K. Smit, K.S.E. Eikema, W. Ubachs, A. Anantathanasarn, R. Notzel,
Passively mode-locked 4.6 GHz and 10.5 GHz quantum dot laser diodes around 1.55 micron with large operating regime
IEEE Journal of Select. Top. in Quant. Electr. 15 (2009) 634-643


H.L. Bethlem, W. Ubachs,
Testing the time invariance of fundamental constants using microwave spectroscopy on diatomic radicals
Including the Discussion
Faraday Disc. 142, 25-36 (2009)

E.J. Salumbides, A. Khramov, W. Ubachs,
High-resolution 2+1 REMPI study of the a'' ¹S_g⁺ state in N₂
J. Phys. Chem. A 113 (2009) 2383-2386


L. van der Sneppen, C. Gooijer, W. Ubachs, F. Ariese,
Cavity Ring-Down spectroscopy in analytical chemistry
In: Cavity Ring-Down Spectroscopy; Techniques and Applications
Eds. G. Berden and R. Engeln, Blackwell Publishing (Wiley), 2009, p. 89-112

F. Hamann, N. Kanekar, J.X. Prochaska, M.T. Murphy, N. Milutinovic, S. Ellison, W. Ubachs, G. Ferland
New results on Quasar Outflows
Proceedings IAU symposium 267, 399 (2009)

E.J. Salumbides, D. Bailly, A. Khramov, A.L. Wolf, K.S.E. Eikema, M. Vervloet, W. Ubachs,
Improved laboratory values of the H₂ Lyman and Werner lines
for constraining time variation of the proton-to-electron mass ratio
Phys. Rev. Lett. 101, 223001 (2008); Supplementary Material.

M.O. Vieitez, T.I. Ivanov, E.Reinhold, C.A. de Lange, W. Ubachs,
Observation of a Rydberg series in H⁺H^-: A heavy Bohr atom
Phys. Rev. Lett. 101, 163001 (2008)


R. Flatscher, A. Cabral, M. Abreu, A.L. Verlaan, S. Witte, W. Ubachs
Absolute Long-distance measurements with (sub)-micrometer accuracy for formation flight applications
ESA-report, ESA study 20183/NL/HE (2008).


B.R. Lewis, K.G.H. Baldwin, A.N. Heays, S.T. Gibson, J.P. Sprengers, W. Ubachs, M. Fujitake,
Structure and predissociation of the 3ps_u D³S_u⁺ state of N₂;
First extreme ultraviolet and new near-infrared observations with coupled-channels analysis
J. Chem. Phys. 129, 204303 (2008).

D. Ityaksov, H. Linnartz, W. Ubachs,
Deep-UV Rayleigh Scattering of N₂, CH₄ and SF₆
Mol. Phys. 106, 2471 - 2479 (2008)


J.N. Philippson, R.C. Shiell, E.Reinhold, W. Ubachs,
Observation of molecular hyperfine structure in the XUV: the HF C-X spectrum
J. Chem. Phys. 129, 174310 (2008)


B.R. Lewis, K.G.H. Baldwin, J.P. Sprengers, W. Ubachs, G. Stark, K. Yoshino,
Optical observation of C, F, and G³P_u states of N₂
J. Chem. Phys. 129 (2008) 164305

L. van der Sneppen, C. Gooijer, W. Ubachs, F. Ariese,
Cavity Ring-Down spectroscopy in chemistry
In: Lasers in Chemistry; Ed. M. Lackner, Wiley-VCH (2008)

H.L. Bethlem, M. Kajita, B. Sartakov, G. Meijer, W. Ubachs,
Prospects for precision measurements on ammonia molecules in a molecular fountain
Eur. Phys. Journal Special Topics 163 (2008) 55-69

M. Roudjane, T.I. Ivanov, M.O. Vieitez, C.A. de Lange, W.U.L. Tchang-Brillet, W. Ubachs,
Extreme ultraviolet laser calibration of D₂ Lyman and Werner transitions
Mol. Phys. 106, 1193-1197 (2008)

A.L. Wolf, S.A. van den Berg, Ch. Gohle, E.J. Salumbides, W. Ubachs, K.S.E. Eikema,
Frequency metrology on the 4s ²S_1/2 - 4p ²P_1/2 transition in ⁴⁰Ca⁺ for comparison with quasar data
Phys. Rev. A 78, 032511 (2008)


T.I. Ivanov, E.J. Salumbides, M.O. Vieitez, P.C. Cacciani, C.A. de Lange, W. Ubachs,
Extreme ultraviolet laser metrology of O I transitions
Monthly Notices Roy. Astron. Society Letters 389, L4-L7 (2008)


T.I. Ivanov, M. Roudjane, M.O. Vieitez, C.A. de Lange, W.U.L. Tchang-Brillet, W. Ubachs,
On a variation of the proton-electron mass ratio HD as a probe for detecting mass variation on a cosmological time scale
Phys. Rev. Lett. 100, 093007 (2008)

D. Ityaksov, H. Linnartz, W. Ubachs,
Deep-UV absorption and Rayleigh scattering of carbon dioxide
Chem. Phys. Lett. 462, 31-34 (2008)


D.Z. Kandula, A. Renault, Ch. Gohle, A.L. Wolf, S. Witte, W. Hogervorst, W. Ubachs, K.S.E. Eikema,
Ultrafast double-pulse parametric amplification for precision Ramsey metrology
Opt. Express 16 (2008) 7071-7082


M.O. Vieitez, T.I. Ivanov, C.A. de Lange, W. Ubachs, A.N. Heays, B.R. Lewis, G. Stark,
Interactions of the 3pp_u c¹P_u(v=2) Rydberg-complex member in isotopic N₂
J. Chem. Phys. 128 134313 (2008)

F. Brandi, F. Giammanco, W. Ubachs,
Plasma-dynamically induced frequency shifts in high-order harmonic generation in nitrogen
Laser Physics 18, 585-591 (2008)

M.O. Vieitez, T.I. Ivanov, W. Ubachs, B.R. Lewis, C.A. de Lange,
On the complexity of the absorption spectrum of molecular nitrogen
J. Molecular Liquids 141, 110-117 (2008)

E.J. Salumbides, K.S.E. Eikema, W. Ubachs, U. Hollenstein, H. Knoeckel, E. Tiemann,
Improved potentials and Born-Oppenheimer corrections by new measurements
of transitions of ¹²⁹I₂ and ¹²⁷I¹²⁹I in the B³P_u - X¹S_g band system
Eur. Phys. Journ. D 47, 171-179 (2008)

L. van der Sneppen, J. B. Buijs, C. Gooijer, W. Ubachs, F. Ariese
Evanescent Wave Cavity Ring-Down spectroscopy for enhanced dectection
of surface binding under flow injection analysis
Applied Spectr. 62, 649-654 (2008)

T.I. Ivanov, M.O. Vieitez, C.A. de Lange, W. Ubachs,
Frequency calibration of B¹S_u⁺ - X¹S_g⁺ (6,0) Lyman lines in H₂ for comparison with quasar data
J. Phys. B 41 (2008) 035702

S. Hannemann, E.-J. van Duijn, W. Ubachs,
A narrow-band injection-seeded pulsed titanium:sapphire oscillator-amplifier system
with on-line chirp analysis for high-resolution spectroscopy
Rev. Sci. Instrum. 78 (2007) 103102

W. Ubachs, R. Buning, K.S.E. Eikema, E. Reinhold,
On a possible variation of the proton-electron mass ratio; H₂ spectra in the line of sight of high-redshift quasars and in the laboratory
J. Mol. Spectr. 241 (2007) 155-179


M.O. Vieitez, T.I. Ivanov, J.P. Sprengers, C.A. de Lange, W. Ubachs, B.R. Lewis, G. Stark
Quantum-interference effects in the o¹P_u(v=1) - b¹P_u(v=9) Rydberg-valence complex of molecular nitrogen
Mol. Phys. 105 (2007) 1543-1557


S. Hannemann, E.J. Salumbides, W. Ubachs,
Reducing the first order Doppler shift in a Sagnac interferometer
Optics Lett. 32 (2007) 1381-1383

L. van der Sneppen, F. Ariese, C. Gooijer, W. Ubachs,
Cavity ring-down spectroscopy for detection in liquid chromatography at UV wavelengths using standard cuvettes in a zero-degree geometry
J. Chromatogr. A 1148 (2007) 184-188

W. Ubachs, R. Buning, E.J. Salumbides, S. Hannemann, H.L. Bethlem, D. Bailly, M. Vervloet, L. Kaper, M.T. Murphy
On a variation of the proton-electron mass ratio
Proceedings of the XVIII International Conference on Laser Spectroscopy 2007
World Scientific; Eds: L. Hollberg, J. Bergquist, M. Kasevich

R.T. Zinkstok, S. Witte, A. Renault, D. Kandula, A.L. Wolf, W. Ubachs, W. Hogervorst, K.S.E. Eikema
Frequency comb laser spectroscopy at vacuum ultraviolet wavelengths and beyond
IQEC Conference Proceedings 2007

E. Reinhold, R. Buning, U. Hollenstein, A. Ivanchik, P. Petitjean, W. Ubachs,
Indication of a cosmological variation of the proton-electron mass ratio based on laboratory measurement and reanalysis of H₂ spectra
Phys. Rev. Lett. 96 (2006) 151101
Supplementary Material to the paper: EPAPS

W. Ubachs, R. Buning, E. Reinhold,
Is er toch variatie van Natuurconstanten ?
Ned. Tijdschr. v. Natuurk. 72, 184-185 (2006).

S. Hannemann, E.J. Salumbides, S. Witte, R. Zinkstok, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs,
Frequency metrology on the EF¹S⁺_g- X¹S⁺_g transition in H₂, HD and D₂
Phys. Rev. A 74, 062514 (2006).

W. Ubachs
Precision spectroscopy of H₂ and a possible variation of m_p/m_e over cosmological time
AIP Conf. Prod. 869, 37 (2006).

E.J. Salumbides, S. Hannemann, K.S.E. Eikema, W. Ubachs,
Isotopically-resolved calibration of the 285-nm Mg I resonance line for comparison with quasar absorptions
Mon. Notices Roy. Astron. Soc. 373 (2006) L41-L44


S. Witte, R. Th. Zinkstok, A.L. Wolf, W. Hogervorst, W. Ubachs, K.S.E. Eikema,
A source of 2 terawatt, 2.7 cycle laser pulses based on noncollinear optical parametric chirped amplification
Opt. Express 14, 8168-8177 (2006)


S. Hannemann, E.J. Salumbides, S. Witte, R. Zinkstok, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs,
Frequency metrology on the Mg 3s² - 3s4p line for comparison with quasar data
Phys. Rev. A 74, 012505 (2006).

R.T. Zinkstok, S. Witte, W. Ubachs, W. Hogervorst, K.S.E. Eikema,
Frequency comb metrology laser spectroscopy in the vacuum ultraviolet
Phys. Rev. A 73, 061801(R) (2006)


L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs,
Cavity ring-down spectroscopy for detection in liquid chromatography:
extension to tunable sources and UV wavelengths
Appl. Spectr. 60, 931-935 (2006)

E.J. Salumbides, K.S.E. Eikema, W. Ubachs, U. Hollenstein, H. Knoeckel, E. Tiemann,
The hyperfine structure of ¹²⁹I₂ and ¹²⁷I¹²⁹I in the B³P_u - X¹S_g band system
Mol. Phys. 104, 2641-2652 (2006)

O. Naumenko, M. Sneep, M. Tanaka, S.V. Shirin, W. Ubachs, J. Tennyson,
Cavity ring-down spectroscopy of H₂¹⁷O in the range 16570 -17125 cm^-1
Supplementary Material
J. Mol. Spectr. 237, 63-69 (2006)

U. Hollenstein, E. Reinhold, C.A. de Lange, W. Ubachs,
High resolution VUV-laser spectroscopic study of the B¹S_(u)⁺ (v') - X¹S_(g)⁺ (0), v'=0-2 Lyman bands in H₂ and HD
J. Phys. B. 39 (2006) L195-L201

F. Brandi, F. Giammanco, W. Ubachs
Spectral redshift in harmonic generation from plasma dynamics in the laser focus
Phys. Rev. Lett. 96 (2006) 123904


L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs,
Improving absorbance detection in Liquid Chromatography with Cavity Ring-Down spectroscopy
Anal. Chim. Acta 558, 2-6 (2006).

J.P. Sprengers, W. Ubachs
Lifetimes and transition frequencies of several singlet ungerade states in N₂ between 100000 - 106000 cm^-1
J. Mol. Spectr. 235, 176-180 (2006).

M. Sneep, D. Ityaksov, I. Aben, H. Linnartz, W. Ubachs,
Temperature dependent cross sections of O₂-O₂ collision-induced absorption resonances at 477 nm and 577 nm
J. of Quant. Spectr. Rad. Transfer, 98 (2006) 405-424

L. van der Sneppen, F. Ariese, C. Gooijer, A Wiskerke, W. Ubachs
Cavity Ring-Down spectroscopy as a detector in liquid chromatography
In: Advances in Spectroscopy for Lasers and Sensing, Springer, 2006, Part 3, 540

R.Th. Zinkstok, S. Witte, W. Ubachs, W. Hogervorst, K.S.E. Eikema
Demonstration of Frequency Comb Laser Spectroscopy in the Vacuum-Ultraviolet
15th International Conference on Ultrafast Phenomena, 2006

R.C. Shiell, E. Reinhold, F. Magnus, W. Ubachs,
Control of diabatic vs. adiabatic field dissociation in a heavy Rydberg system
Phys. Rev. Lett. 95 (2005) 213002


S. Witte, R.T. Zinkstok, W. Ubachs, W. Hogervorst, K.S.E. Eikema
Deep ultraviolet quantum-interference metrology with ultrashort laser pulses
Science 307, 400-403 (2005).
See also: Perspective on this paper

B.R. Lewis, S.T. Gibson, J.P. Sprengers, W. Ubachs, A. Johansson, C.-G. Wahlstrom,
Lifetime and predissociation yield of ¹⁴N₂ b¹P_u(v=1) revisited: effects of rotation
J. Chem. Phys. 123, 236101 (2005).

E.J. Salumbides, J.P. Sprengers, E. Reinhold, W. Ubachs
High precision frequency calibration of N I lines in the XUV domain
J. Phys. B 38, L383-L387 (2005).

S. Hannemann, G.R. Wu, E.-J. van Duijn, W. Ubachs, Ph. Cosby,
Pressure broadening and fine-structure dependent predissociation in oxygen B³S_u^-, v=0
J. Chem. Phys. 123, 174318 (2005)

L. K. Cheng, R. Koops, A. Wielders, W. Ubachs
Alternative fringe sensor for DARWIN mission
Proc. SPIE Int. Soc. Opt. Eng. 5905, 59051E (2005).

L. K. Cheng, R. Koops, A. Wielders, W. Ubachs
Development of a fringe sensor based on 3x3 fiber optic coupler for space interferometry
Proc. SPIE Int. Soc. Opt. Eng. 5855, 1004 (2005).

J.P. Sprengers, E. Reinhold, W. Ubachs, K.G.H. Baldwin, B.R. Lewis
Optical observation of the 3ss_g F³P_u Rydberg state of N₂
J. Chem. Phys. 123, 144315 (2005).

S. Hannemann, U. Hollenstein, E.-J. van Duijn, W. Ubachs,
Production of narrowband tunable XUV radiation by non-collinear resonance enhanced four-wave mixing
Opt. Lett. 30, 1494-1496 (2005).

S. Hannemann, E.-J. van Duijn, W. Ubachs,
Deep-UV high resolution cavity ring-down spectroscopy of the Schumann-Runge bands in ¹⁶O₂ and ¹⁸O₂ at wavelengths 197 - 203 nm
J. Mol. Spectr. 232, 33-38 (2005).

I. Labazan, E. Reinhold, W. Ubachs, V.V. Flambaum
Wavelength calibration of the C I line at 94.5 nm for comparison with quasar data
Phys. Rev. A 71, 040501(R) (2005).

B. Bahnev, L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs
Miniaturized Cavity Ring-Down detection in a liquid flow cell
Anal. Chem. 77, 1188-1191 (2005).

I. Velchev, W. Ubachs
Statistical properties of the Stokes signal in stimulated Brillouin scattering pulse compressors
Phys. Rev. A 71, 043810 (2005).

J.P. Sprengers, W. Ubachs, K.G.H. Baldwin
Isotopic variation of experimental lifetimes for the lowest ¹P_u states in N₂
J. Chem. Phys. 122, 144301 (2005).

E. Reinhold, W. Ubachs
Heavy Rydberg states
Mol. Phys. 103, 1329-1352 (2005).

F. Giammanco, A. Pirri, F. Brandi, M. Barkauskas, W. Ubachs
Measurements of chirp-induced frequency shift in high-harmonic generation in xenon
Laser Physics 15, 328-333 (2005).

M. Barkauskas, F. Brandi, F. Giammanco, D. Neshev, A. Pirri, W. Ubachs
A novel-type tunable and narrowband extreme ultraviolet radiation source based on high-harmonic conversion of picosecond laser pulses
J. Electr. Spectr. Rel. Phen. 144-147, 1151-1155 (2005).

W. Ubachs
High resolution molecular physics studies using a laser-based tunable XUV source at 10⁷ resolving power
J. Electr. Spectr. Rel. Phen. 144-147, 97-101 (2005).

M. Sneep, W. Ubachs
Direct measurement of the Rayleigh scattering cross section in various gases
J. Quant. Spectr. Rad. Transfer 92, 293-310 (2005).

S. Witte, R.T. Zinkstok, W. Ubachs, W. Hogervorst, K.S.E. Eikema,
Demonstration of quantum-interference metrology with amplified ultrashort laser pulses
CLEO Conference Proceedings (2005)

W. Ubachs, E. Reinhold,
Highly accurate H₂ Lyman and Werner band laboratory measurements and an improved constraint on a cosmological variation of the Proton-to-electron mass-ratio
Phys. Rev. Lett. 92 (2004) 101302

W. Ubachs, E. Reinhold
Natuurconstanten, variabel of constant ?
Ned. Tijdschr. v. Natuurkunde 70, 208-211 (2004).

M. Eidelsberg, F. Launay, K. Ito, T. Matsui, P.C. Hinnen, E. Reinhold, W. Ubachs, K.P. Huber
Rydberg-valence interactions of CO, and spectroscopic evidence characterizing the C'¹S⁺ valence state
J. Chem. Phys. 121, 292-308 (2004).

M. Sneep, S. Hannemann, E.-J. van Duijn, W. Ubachs
Deep-UV Cavity Ring-Down Spectroscopy
Opt. Lett. 29, 1378-1380 (2004).

J. Philip, J.P. Sprengers, Th. Pielage, C.A. de Lange, W. Ubachs, E. Reinhold
Highly accurate transition frequencies in the H₂ Lyman and Werner absorption bands
Can. J. Chem. 82, 713-722 (2004).

M. Tanaka, M. Sneep, W. Ubachs, J. Tennyson,
Cavity-Ring-Down Spectroscopy of H₂¹⁸O in the 16570 -- 17120 cm^-1 frequency range
J. Mol. Spectr. 226, 1-6 (2004).

J.P. Sprengers, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, B.R. Lewis, W. Ubachs
Pump-probe lifetime measurements on singlet ungerade states in molecular nitrogen
Chem. Phys. Lett. 389, 348-351 (2004).

J.P. Sprengers, W. Ubachs, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, R. Lang, B.R. Lewis, S.T. Gibson
Lifetime and predissociation yield of ¹⁴N₂ b¹Pi_u(v=1)
J. Chem. Phys. 120, 8973-8978 (2004).


P. Cacciani, W. Ubachs
High resolution study of Q-branches in the E¹P - X¹S⁺ (0,0) band of ¹²C¹⁶O, ¹³C¹⁶O and ¹³C¹⁸O
J. Mol. Spectr. 225, 62-65 (2004).

J. Philip, J.P. Sprengers, P. Cacciani, C.A. de Lange, W. Ubachs
Frequency-mixing scheme for the production of tunable narrowband XUV radiation (91-95 nm)
Appl. Phys. B 78, 737-743 (2004).

E. Witkowicz, H. Linnartz, C.A. de Lange, W. Ubachs, A. Sfounis, M. Massaouti, M. Velegrakis
Mass spectrometric and laser spectroscopic characterization of a supersonic planar plasma expansion
Int. J. Mass Spectr. 232, 25-29 (2004).

K.G.H. Baldwin, J.P. Sprengers, W. Ubachs, B.R. Lewis, S.T. Gibson
Ultrahigh resolution pulsed XUV laser applications: Lifetimes for the excited ¹P_i states of molecular nitrogen
Trends in Optics and Photonics. 97, 549-551 (2004).

F. Brandi, D. Neshev, W. Ubachs
High-order harmonic generation yielding tunable extreme-ultraviolet radiation of high spectral purity
Phys. Rev. Lett. 91, 163901 (2003).

G. Greetham, U. Hollenstein, R. Seiler, W. Ubachs, F. Merkt
High resolution VUV photoionization spectroscopy of HD between the X²S_g⁺, v⁺=0 and v⁺=1 thresholds
Phys. Chem. Chem. Phys. 5, 2528-2534 (2003).

J.P. Sprengers, W. Ubachs, K.G.H. Baldwin, B.R. Lewis, W.-U.L. Tchang-Brillet
Extreme ultraviolet laser excitation of isotopic molecular nitrogen: the dipole allowed spectrum of ¹⁵N₂ and ¹⁴N¹⁵N
J. Chem. Phys. 119 (2003) 3160-3173
Additional material in EPAPS archive: Data

F. Brandi, I. Velchev, D. Neshev, W. Hogervorst, W. Ubachs
A novel narrow-band wavelength-tunable laser system delivering 300 ps high-energy pulses in the near-infrared
Rev. Sci. Instr. 74, 32-37 (2003).


J.C.J. Koelemeij, A. de Lange, W. Ubachs
Search for outer-well states above the ionization potential in H₂
Chem. Phys. 287, 349-354 (2003).

M. Sneep, W. Ubachs
Cavity-Ring down measurement of the O₂-O₂ collision-induced absorption resonance at 477 nm at sub-atmospheric pressures
J. Quant. Spectr. Rad. Transfer 78, 171-178 (2003).

M. Sneep, W. Ubachs
Cavity-Ring down spectroscopy of O₂-O₂ collisional induced absorption
In: Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere,
NATO Science series: IV: Earth and Environmental sciences Vol 27; eds. C. Camy-Peret, A. Vigasin (2003).

E. Reinhold, W. Ubachs
Observation of coherent wave packets in a heavy Rydberg system
Phys. Rev. Lett. 88, 013001 (2002).

F. Brandi, W. Hogervorst, W. Ubachs
High resolution vacuum-ultraviolet and ultraviolet photionization spectroscopy of krypton
J. Phys. B 35, 1071-1084 (2002).


P. Cacciani, F. Brandi, J.P. Sprengers, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, W. Ubachs
Predissociation of the 4pp L¹P Rydberg state of carbon monoxide
Chem. Phys. 282, 63-73 (2002).

G. Berden, G. Meijer, W. Ubachs
Spectroscopic Applications using Ring-Down cavities
In: Cavity Enhanced Spectroscopies; Eds: Van Zee, Looney, Academic Press (2002)
Experimental methods in the Physical Sciences Vol. 40, 47-82 (2002).

A. de Lange, R. Lang, W.J. van der Zande, W. Ubachs
Highly excited states of gerade symmetry in molecular nitrogen
J. Chem. Phys. 116, 7893-7901 (2002).

Th. Pielage, A. de Lange, F. Brandi, W. Ubachs
Bound energy levels at the n=2 dissociation threshold in HD
Chem. Phys. Lett. 366, 583-587 (2002).

R. Lang, A.N. Maurellis, W.J. van der Zande, I. Aben, J. Landgraf, W. Ubachs
Forward modeling and retrieval of water vapor from GOME: Treatment of narrow band absorption spectra
J. Geoph. Res. 107 D (2002) doi:10.1029/2001JD001453

A. de Lange, E. Reinhold, W. Ubachs
Phenomena of g-u symmetry-breakdown in HD
Intern. Reviews in Phys. Chemistry 21, 257-275 (2002).

A. de Lange, E. Reinhold, W. Ubachs
Precision spectroscopy on some g symmetry states in H₂ and determination of the ionization potential
Phys. Rev. A 65, 064501 (2002).

K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst
Precision spectroscopy on the Lyman-a transitions of H and He
In: "Laser Physics at the limit"; eds H. Figger, D. Meschede, C. Zimmerman Springer Verlag, Berlin-Heidelberg (2002) p 107-113

E. Reinhold, W. Ubachs
Exotisch atoom met verzwaard elektron (in Dutch)
Ned. Tijdschr. v. Natuurkunde 68, 118-120 (2002).

A. de Lange, W. Hogervorst, W. Ubachs, L. Wolniewicz
Double-well states of ungerade symmetry in H₂; first observation and ab initio calculation
Phys. Rev. Lett. 86, 2988-2991 (2001).

H. Naus, I.H.M. van Stokkum, W. Hogervorst, W. Ubachs,
Quantitative analysis of decay transients applied to a multi-mode pulsed cavity ring-down experiment
Applied Optics 40, 4416-4426 (2001).

W. Ubachs, R. Lang, I. Velchev, W.-U L. Tchang-Brillet, A. Johansson, Z.S. Li, V. Lokhnygin, C.-G. Wahlstrom
Lifetime measurements on the c₄' ¹S_u⁺, v=0,1 and 2 states of molecular nitrogen
Chem. Phys. 270, 215-225 (2001).

F. Brandi, I. Velchev, W. Hogervorst, W. Ubachs
High-resolution VUV spectroscopy of Xe Hyperfine splittings, Isotope shifts and isotope dependent Ionization energies
Phys. Rev. A 64, 032505 (2001).

P. Cacciani, F. Brandi, I. Velchev, C. Lynga, C.-G. Wahlstrom, W. Ubachs
Isotope dependent predissociation in the C¹S⁺, v=0 and v=1 states of CO
Eur. Phys. J. D 15, 47-56 (2001).

I. Velchev, W. Ubachs
Higher-order stimulated Brillouin scattering with non-diffracting beams
Opt. Lett. 26, 530-532 (2001).

G. Bazalgette Courreges-Lacoste, J.P. Sprengers, W. Ubachs, S. Stolte, H. Linnartz
The A²S⁺-X²P transition of CF starting from highly excited vibrational states
J. Mol. Spectr. 205, 341-343 (2001).

H. Naus, W. Ubachs, P.F. Levelt, O.L. Polyansky, N.F. Zobov, J. Tennyson
Cavity-Ring-Down spectroscopy on water vapour in the range 555-604 nm
J. Mol. Spectr. 205, 117-121 (2001).

W. Ubachs
Laboratory studies of Long-range Excited states of H₂
in: Molecular Hydrogen in Space, eds. F. Combes and G. Pineau des Forets, Cambridge University Press, 2000, p 39-46

A. de Lange, E. Reinhold, W. Hogervorst, W. Ubachs
g/u symmetry breaking in HD at the n=2 dissociation limit
Can. J. Phys. 78, 567-578 (2000).

W. Ubachs, I. Velchev, P. Cacciani
Predissociation in the E¹P, v=1 state of the six natural isotopomers of CO
J. Chem. Phys. 113, 547-560 (2000).

E. Reinhold, W. Hogervorst, W. Ubachs
Tunneling and decay dynamics of H¹S_g⁺ outer well states in hydrogen
J. Chem. Phys. 112, 10754-10760 (2000).

S.C. Xu, R. van Dierendonck, W. Hogervorst, W. Ubachs
A dense grid of reference iodine lines for optical frequency calibration in the range 595-655 nm
J. Mol. Spectr. 201, 256-266 (2000). Supplementary Material

W. van der Zande, W. Ubachs
Comment on: First observation of the rotational constants for the homonuclear ion He₂⁺
Phys. Rev. Lett. 84, 3212 (2000).

W. Ubachs, I. Velchev, A. de Lange
Predissociation in b¹P_u, v (v=1,4,5,6) levels of N₂
J. Chem. Phys. 112, 5611-5616 (2000).

H. Naus, W. Ubachs
Experimental Verification of Rayleigh-Scattering Cross sections
Opt. Lett. 25 (2000) 347-349

A.N. Maurellis, R. Lang, W. van der Zande, I. Aben, W. Ubachs
Precipitable water column retrieval from GOME data
Geoph. Res. Lett. 27, 903-906 (2000).

I. Velchev, D. Neshev, W. Hogervorst, W. Ubachs
Pulse compression to the sub-phonon lifetime region by half-cycle gain in transient stimulated Brillouin scattering
IEEE J. of Quant. Electr. 35, 1812-1816 (1999).

C.R. Scheper, C.A. de Lange, E. Reinhold, A. de Lange, W. Ubachs
Dissociation of H₂ in the energy region at the H(n=1) + H(n=3) dissociation threshold after (1+1') resonance-enhanced two photon ionization via the B¹S_u⁺ state
Chem. Phys. Lett. 312, 131-138 (1999).

A. de Lange, W. Ubachs
Observation of the y¹P_g-c₄' ¹S_u⁺ and k¹P_g-c₄' ¹S_u⁺ systems of N₂
Chem. Phys. Lett. 310, 471 (1999).

E. Reinhold, W. Hogervorst, W. Ubachs, L. Wolniewicz
Experimental and theoretical investigation of the HH¹S_g⁺ state in H₂, D₂ and HD and the B"B¹S_u⁺ state in HD
Phys. Rev. A60, 1258 (1999).

I. Velchev, W. Hogervorst, W. Ubachs
Precision VUV spectroscopy of Argon I at 105 nm
J. Phys. B 17, L511 (1999).

R. Teule, S. Stolte, W. Ubachs
Collision-induced E(0_g⁺)-D(0_u⁺) state-to-state energy transfer in I₂
Laser Chemistry 18 (1999) 111-128

H. Naus, W. Ubachs
Visible absorption bands of the (O₂)₂-collision complex at pressures below 760 Torr
Applied Optics 38, 3423-3428 (1999).

H. Naus, K. Navaian, W. Ubachs
The gamma-band of ¹⁶O₂, ¹⁶O¹⁷O, ¹⁷O₂ and ¹⁸O₂
Spectrochimica Acta 55, 1255 (1999).

D. Neshev, I. Velchev, W. Majewski, W. Hogervorst, W. Ubachs
SBS Pulse compression to 200 ps in a compact single-cell setup
Appl. Phys. B68, 671 (1999).

H. Naus, W. Ubachs
The b¹S_g⁺ - X³S_g^- (3,0) band of ¹⁶O₂ and ¹⁸O₂
J. Mol. Spectr. 193, 442-445 (1999).

W. Ubachs, A. de Lange, E. Reinhold, W. Hogervorst,
XUV-multiple resonance excitation of long-range states in molecular hydrogen
In: Laser Spectroscopy XIV International Conference, World Scientific 1999 Eds: R. Blatt et al., p 23-32

R. Lang, A.N. Maurellis, W.J. van der Zande, I. Aben, P. Levelt, H. Naus, W. Ubachs
DOAS-OCM retrieval of Water Vapour from GOME and new CRD Spectroscopy
In: Proc. Eur. Space Agency, Symp. Atmospheric Measurements from Space
ESTEC, Document WPP-161 (1999) pp. 391-394

H. Naus, W. Ubachs
First measurement of the Rayleigh cross section
Conference on Lasers and Electro-Optics Europe, 2000.

E. Reinhold, A. de Lange, W. Hogervorst, and W. Ubachs
Observation of the I' ¹P_g outer well state in H₂ and D₂
J. Chem. Phys. 109, 9772 (1998).

E. Reinhold, W. Hogervorst, and W. Ubachs
Complete g-u symmetry breaking in highly excited valence states of the HD molecule
Chem. Phys. Lett. 296, 411 (1998).

H. Naus, S.J. van der Wiel, W. Ubachs
Cavity-ring-down spectroscopy on the b¹S_g⁺ - X³S_g^- (1,0) band of oxygen isotopomers
J. Mol. Spectr. 192, 162-168 (1998).

P.C. Hinnen, S. Stolte, W. Hogervorst, W. Ubachs
XUV-laser spectrometer for direct absorption measurements; application to CO in the wavelength range 96-97 nm
Journ. of Opt. Soc. Am. B15, 2620-2625 (1998).

P.P. Sorokin, J.H. Glownia, W. Ubachs
Current Status of the H₂ diffuse interstellar bands theory
Faraday Discussion 109, 137-163 (1998); and the Discussion 217-256

W. Hogervorst, K.S.E. Eikema, E. Reinhold, W. Ubachs
Precision XUV-laser spectroscopy of atomic and molecular two-electron systems
Nuclear Physics, A631, 353 (1998).

P. Cacciani, W. Ubachs, P.C. Hinnen, C. Lynga, A. L'Huillier, C.-G. Wahlstrom
Lifetime measurements of the E¹P, v=0 and v=1 states of ¹²C¹⁶O, ¹³C¹⁶O and ¹³C¹⁸O
Astroph. J. Lett. 499, L223 (1998).

S. Schiemann, W. Hogervorst, W. Ubachs
Fourier-transform-limited laser pulses tunable in wavelength and pulse duration (400-2000 ps)
IEEE J. of Quantum Electr. 34 (1998) 407-412

I. Velchev, R. van Dierendonck, W. Hogervorst, W. Ubachs
A dense grid of reference iodine lines for optical frequency calibration in the range 571-596 nm
J. Mol. Spectr. 187 (1998) 21-27. Supplementary Material

E.J. Brinksma, Y.J. Meijer, I.S. McDermid, R.P. Cageao, J.B. Bergwerff, D.P.J. Swart, W. Ubachs, W.A. Matthews, W. Hogervorst, J.W. Hovenier
First LIDAR observations of mesospheric hydroxyl
Geoph. Res. Lett. 25, 51-54 (1998).

E.J. Brinksma, Y.J. Meijer, I.S. McDermid, R.P. Cageao, J.B. Bergwerff, D.P.J. Swart, W. Ubachs, W.A. Matthews, W. Hogervorst, J.W. Hovenier
Correction: First LIDAR observations of mesospheric hydroxyl
Geoph. Res. Lett. 25, 521 (1998).

H. Naus, A. de Lange, W. Ubachs
b¹S_g⁺ - X³S_g^- (0,0) band of oxygen isotopomers in relation to tests of the symmetrization postulate in ¹⁶O₂
Phys. Rev. A56, 4755 (1997).

W. Ubachs, K.S.E. Eikema, W. Hogervorst, P.C. Cacciani
Narrow-band tunable extreme ultaviolet laser source for lifetime measurements and precision spectroscopy
J. Opt. Soc. Am. B14, 2469 (1997).

E. Reinhold, W. Hogervorst, W. Ubachs
Observation of a highly excited long-lived valence state in H₂
Phys. Rev. Lett. 78, 2543 (1997).

S. Schiemann, W. Ubachs, W. Hogervorst
Efficient temporal compression of coherent nanosecond pulses in a compact generator-amplifier setup
IEEE J. of Quantum Electr. 33 (1997) 358

K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst
Lamb shift measurement in the 1 ¹S ground state of helium
Phys. Rev. A55, 1866 (1997).

W. Ubachs
Predissociative decay of the c'₄¹S_u⁺, v=0 state of molecular nitrogen
Chem. Phys. Lett. 268, 201 (1997).

W. Ubachs, P.C. Hinnen, E. Reinhold
Observation of inter-Rydberg transitions in H₂ coinciding with Diffuse Interstellar Bands
Astrophys. J. Lett. 476 (1997) L93

W. Hogervorst, K.S.E. Eikema, W. Vassen, W. Ubachs
QED and the ground state of Helium
In: Atomic Physics 15, H.B. van Linden van den Heuvell, J.T.M. Walraven, M.W. Reynolds eds. (World Scientific, Singapore 1997) 169-179

H. Naus, A. de Lange, W. Ubachs, R. Engeln, G. Berden, G. Meijer
Cavity Ring Down Spectroscop aan zuurstof en zuurstofdimeer (in Dutch)
Van A tot Q 12 (1997) 39

W. Ubachs, I. Aben, W. van der Zande
Stikstof in de Atmosfeer (in Dutch)
Van A tot Q 12 (1997) 61

K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst
Precision measurements in helium at 58 nm: Ground state Lamb shift and the 1 ¹S - 2 ¹P transition isotope shift
Phys. Rev. Lett. 76, 1216 (1996).

R. van Leeuwen, W. Ubachs, P. Camus, W. Hogervorst
Electron correlation in three-body Coulomb states of barium
Phys. Rev. A54, R17 (1996).

P.C. Hinnen, W. Ubachs
Further tests concerning the hypothesis of H₂ as the carrier of the diffuse interstellar bands
Chem. Phys. Lett. 254, 32 (1996).

E. Reinhold, W. Hogervorst, W. Ubachs
High resolution laser spectroscopy of H₂ at 86-90 nm
J. Mol. Spectr. 180, 156 (1996).

R. van Leeuwen, M. Aymar, W. Ubachs, W. Hogervorst
Channel mixing in 4fng autoionizing series of barium
J. Phys. B29, 1007 (1996).

P.C. Hinnen, W. Ubachs
On the hypothesis of H₂ as the carrier of the diffuse interstellar bands
Chem. Phys. Lett. 240, 351-356 (1995).

P.C. Hinnen, S.E. Werners, W. Hogervorst, S. Stolte, W. Ubachs
XUV laser spectroscopy of HD at 92-98 nm
Phys. Rev. A52, 4425 (1995).

W. Ubachs, P.C. Hinnen, P. Hansen, S. Stolte, W. Hogervorst, P. Cacciani
Laser spectroscopic studies of the C¹S⁺, v=0 and v=1 states of CO
J. Mol. Spectr. 174, 388-396 (1995).

P. Cacciani, W. Hogervorst, W. Ubachs
Accidental predissociation phenomena in the E¹P, v=0 and v=1 states of ¹²C¹⁶O and ¹³C¹⁶O
J. Chem. Phys. 102, 8308 (1995).

R. van Leeuwen, W. Ubachs, W. Hogervorst, M. Aymar, E. Luc-Koenig
Interference effects in the autoionization of 4f7h and 6dni states of barium
Phys. Rev. A52, 4567 (1995).

E. Luc-Koenig, M. Aymar, R. van Leeuwen, W. Ubachs, W. Hogervorst
Polarization effects in autoionization processes: the 5d5g states in barium
Phys. Rev. A52, 208 (1995).

W. Ubachs
Resonant Ionization spectroscopy in the XUV spectral region
AIP Conf. Proc. 329, 283-288 (1995), Res. Ion. Spectroscopy 1994, AIP Press 1995

K.S.E. Eikema, W. Ubachs, W. Hogervorst
Isotope shift in the neon ground state by XUV-laser spectroscopy at 74 nm
Phys. Rev. A49, 803 (1994).

K.S.E. Eikema, W. Hogervorst, W. Ubachs
Predissociation in carbon monoxide: dependence on rotational state, parity and isotope
Chem. Phys. 181, 217 (1994).

W. Ubachs, K.S.E. Eikema, P.F. Levelt, W. Hogervorst, M. Drabbels, W.L. Meerts, J.J. ter Meulen
Accurate determination of predissociation rates and transition frequencies for Carbon Monoxide
Astrophys. J. Lett. 427, L55 (1994).

K.S.E. Eikema, W. Hogervorst, W. Ubachs
On the determination of a heterogeneous vs a homogeneous perturbation in a diatomic molecule: the K¹S⁺, v=0 state of ¹³C¹⁸O
J. Mol. Spectr. 163, 19-26 (1994).

P.C. Hinnen, W. Hogervorst, S. Stolte, W. Ubachs
Sub-Doppler laser spectroscopy of H₂ and D₂ in the range 91-98 nm
Can. J. Phys. 72, 1032-1042 (1994).

P.C. Hinnen, W. Hogervorst, S. Stolte, W. Ubachs
High-resolution laser spectroscopy on H₂ at 97-98 nm
Appl. Phys. B 59, 307-310 (1994).

R. van Leeuwen, W. Ubachs, W. Hogervorst
Autoionization of low-lying 5dng states in barium
J. of Phys. B 27, 3891 (1994).

K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst
First laser excitation of the ⁴He 1 ¹S - 2 ¹P resonance line at 58 nm
Phys. Rev. Lett. 71, 1690 (1993).

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Linewidth effects in resonant CARS processes
Opt. Comm. 95, 97 (1993).

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Theory of rotational linestrengths for resonant four-wave-mixing processes in gaseous media with application to CARS
Chem. Phys. 169, 113 (1993).

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Resonance CARS in Br₂
Chem. Phys. Lett. 198, 149 (1993).

W. Ubachs, K.S.E. Eikema, W. Hogervorst
Narrowband extreme ultraviolet radiation tunable in the range 90.5-95 nm: application to spectroscopy of N₂
Appl. Phys. B57 (1993) 411-416

W. Ubachs, I. Aben, J.B. Milan, G.J. Somsen, A.G. Stuiver, W. Hogervorst
Radiative and collisional relaxation of a single rovibrational quantum state of I₂: E(0⁺_g), n=8, J=56
Chem. Phys. 174, 285 (1993).

P.F. Levelt, K.S.E. Eikema, S. Stolte, W. Hogervorst, W. Ubachs
XUV-laser excitation of molecular fluorine
Chem. Phys. Lett. 210, 307 (1993).

G. Kuik, R. van Leeuwen, R. de Graaf, W. Vassen, W. Ubachs, W. Hogervorst
Laser Spectroscopy of doubly-excited states in barium
Am. Inst. Phys. Conf. Proc. 275, 353-362 (1993).

W. Ubachs
Predissociatie: Kortlevende eigentoestanden of Intramolekulaire dynamika
Van A tot Q, 5, Dec 1993, 2-7 (in Dutch)

P.F. Levelt, W. Ubachs
XUV-laser spectroscopy on the c₄' ¹S_u⁺, v=0 and c₃ ¹P_u, v=0 Rydberg states of N₂
Chem. Phys. 163, 263 (1992).

P.F. Levelt, W. Ubachs, W. Hogervorst
Extreme ultraviolet laser spectroscopy on CO in the 91-100 nm range
J. Chem. Phys. 97, 7160 (1992).

P.F. Levelt, W. Ubachs, W. Hogervorst
XUV laser spectroscopy on CO: isotope selective predissociation rates
J. de Physique II France 2, 801-812 (1992).

R.J. de Graaff, W. Ubachs, W. Hogervorst
4fnf doubly-excited autoionizing series in barium
Phys. Rev. A45, 166 (1992).

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Polarization effects in resonant four-wave mixing processes
Mol. Phys. 76, 591 (1992).

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Rotational band structures in resonance CARS of I₂
In: Coherent Raman Spectrsocopy,
Eds: E.M. Castellucci, R. Righini, P. Foggi, World Scientific (1992) 81-84

I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst
Multiple resonance enhanced four-wave mixing processes in I₂
Phys. Rev. A76, 5881 (1991).

M. Abutaleb, R.J. de Graaff, W. Ubachs, W. Hogervorst
The 5dnp and 5dnf J=1 autoionizing series of Ba in one-photon laser excitation from the 6s^{2 1}S₀ ground state
J. Phys. B24, 3565-3573 (1991).

M. Abutaleb, R.J. de Graaff, W. Ubachs, W. Hogervorst
6p_1/2,3/2nf J=1-5 autoionizing series of Barium
Phys. Rev. A44, 4187 (1991).

R.J. de Graaff, W. Ubachs, W. Hogervorst, and M. Abutaleb
Narrow 6p_1/2,3/2np J=1 autoionizing Rydberg series in Barium and their interaction with 6p_3/2nf states
Phys. Rev. A42, 5473 (1990).

W. Ubachs and J.J. ter Meulen
Comment on: Lifetime of the A²S⁺, v=0 state of SH
J. Chem. Phys. 92, 2121-2122 (1990).

I. Aben, P. Levelt, W. Ubachs, W. Hogervorst
Resonance CARS in Br₂ molecules and Br atoms
Inst. Phys. Conf. Series 114, 193-194 (1990).

W. Ubachs, L.M. Tashiro, and R.N. Zare
Study of the N₂ b¹P_u state via 1+1 multiphoton ionization
Chem. Phys. 130, 1 (1989).

L.M. Tashiro, W. Ubachs, and R.N. Zare
The HF and DF B¹S⁺-X¹S⁺ and C¹P-X¹S⁺ band systems studied by 1 XUV +1 UV resonance enhanced multiphoton ionization
J. Mol. Spectr. 138, 89 (1989).

G. Meijer, W. Ubachs, J.J. ter Meulen, and A. Dymanus
High resolution Lamb-dip spectroscopy on OD and SiCl in a molecular beam
Chem. Phys. Lett. 139, 603 (1987).

W. Ubachs, G. Meijer, J.J. ter Meulen, and A. Dymanus
High resolution laser spectroscopy on the c¹P - a¹D transition in NH
J. Mol. Spectr. 115, 88 (1986).

W. Ubachs, G. Meijer, J.J. ter Meulen, and A. Dymanus
Hyperfine structure and Lifetime of the C²S⁺ state of CH
J. Chem. Phys. 84, 3032-3041 (1986).

W. Ubachs, W. van Herpen, J.J. ter Meulen, and A. Dymanus
Hyperfine structure and L-doubling in the A²D state of CH: observation of an internal hyperfine perturbation
J. Chem. Phys. 84, 6575-6580 (1986).

J.J. ter Meulen, W. Ubachs, and A. Dymanus
Observation of rho-doublet transitions in OH (A²S⁺) by UV-microwave double resonance in a molecular beam
Chem. Phys. Lett. 129, 533 (1986).

W. Ubachs, A.P.J. van Deursen, A.R. de Vroomen, and A. Arko
Fermi surface measurements of UPd₃
Solid. State Comm. 60, 7 (1986).

W. Ubachs, J.J. ter Meulen, and A. Dymanus
High resolution laser spectroscopy on the A³P - X³S^- transition of NH
Can. J. Phys. 62, 1374-1391 (1984).

J.J. ter Meulen, W. Ubachs, and A. Dymanus
UV-microwave double resonance spectroscopy on OH
Springer Series in Optical Sciences 40, 345-346 (1983).

W. Ubachs, J.J. ter Meulen, and A. Dymanus
High resolution laser spectroscopy on SH in a molecular beam
Springer Series in Optical Sciences 40, 157-158 (1983).

W. Ubachs, J.J. ter Meulen, and A. Dymanus
High resolution molecular beam spectroscopy on the A²S⁺, v=0 state of SH
Chem. Phys. Lett. 101, 1 (1983)