Master and Bachelorprojects
For up-to-date information please contact the group. The following is a list of possible masters and bachelors projects bound into the ongoing research projects (see research pages), but according to the personal interest of a candidate, we can always discuss further possibilities. Students can participate in all these projects at the Masters level (with a full year of involvement) or at the Bachelors level (6 weeks project). In any case if you are interested in conducting a masters or a bachelors research project please contact one of the scientific staff members in our group: W. Ubachs, K. Eikema, W. Vassen. H.L. Bethlem, J. Koelemeij, or one of the Appointed special professors: I. Aben, L. Kaper, and H. Linnartz.
Phase-controlled ultrafast nonlinear optics and spectroscopy
We are setting up a new powerful femtosecond laser system to study extreme non-linear optics (such as X-ray generation) and high precision spectroscopy (fundamental tests of CPT and QED). Using highly advanced techniques, the electromagnetic wave of the laser pulses will be completely controlled in absolute phase and frequency evolution. If this goal is reached, new phenomena in non-linear optics can be studied. Examples are generation of single X-ray pulses as short as a few hundred attoseconds, and precision spectroscopy of antihydrogen and helium with phase-coherent pulses.Detailed projects are:
- Femtosecond phase stabilization using photonic structure fiber.
- Pulse phase-evolution control using an advanced modulator and genetic search algorithms.
- Coherent femtosecond excitation on a two-photon transition in Rb.
- Investigation and control of phase stability in multi-pass amplification.
Time variation of fundamental constants - Astronomy project
Recently we found indication that the proton-electron mass ratio may be subject to change on a cosmological time scale (see: website). This should be tested further by investigation of spectral data on H2 absorptions at high-redshift detected in the line of sight of quasars. Such data are currently obtained from large telescopes (VLT-ESO- Chile and Keck-Hawaii). We seek a student interested in an astronomy project to carry out this research under supervision of Prof. W. Ubachs, jointly with Prof. Lex Kaper.
Contact: Wim Ubachs
Time variation of fundamental constants - Laser spectroscopic project
Recently we found indication that the proton-electron mass ratio may be subject to change on a cosmological time scale (see: website). Such variation can in principle also be detected on a laboratory time scale, form the spectrum of hydrogen molecules, measured at extreme accuracy. Such a project is underway in the Laser Centre VU. The very weak quadrupole spectrum of H2 lends itself for such a test a variation of constants.
Contact: Wim Ubachs
Synchrotron studies
We are involved in performing spectroscopic studies with the new SOLEIL synchrotron, built in Paris. One of the beam lines has been equipped with a high-resolution (the highest resolution ever) Fourier-transform spectroemeter that is operable in the extreme ultraviolet wavelength range (DESIRS); it is the first of its kind in the world. We will employ this beamline to reinvestigate the hydrogen spectrum (H2, HD and D2 isotopes) in connection to the problem of variation of fundamental constants. We are looking for a student who will analyse the observed line intensities in the absorption spectra of hydorgen.
Contact:Wim Ubachs
Cavity Ring-down detection of atmospheric molecules
Cavity ring-down is a sensitive detection technique for molecules in the gas phase that is also absolute, i.e. absolute absorption cross sections can be determined. Currently we are investigating absorption spectra of molecules of atmospheric relevance: oxygen, nitrogen, nitric oxide, methane. Apart from bound state absorptions we are also able to determine scattering cross sections, such as for Rayleigh scattering. Novelty of our group is that we can perform these studies not only in the near-infrared, visible, ultraviolet wavelength ranges, but also in the deep-ultraviolet. Students can take up the task to study the spectrum of one molecule.
Supervisor: Wim Ubachs and Harold Linnartz.
XUV spectroscopy
In the Laser centre we built a laser system that delivers tunable and narrowband radiation in the range of the extreme ultraviolet. This system is used in a variety of studies investigating highly excited states of molecules. Currently we focus on probing so-called ion-pair states, or heavy-Rydberg states, a new class of electronic states that should occur in all molecules.
Supervisor: Wim Ubachs
Bose-Einstein Condensation of Triplet Helium-4 Atoms
Helium-4 atoms are cooled and trapped, with laser light tuned to the 23S-23P transition, to temperatures ~1 mK above absolute zero. We are in the process of trapping the atoms in a magnetic trap and cooling them further also increasing the density. This should lead to Bose-Einstein condensation at a temperature of ~1 mK. In this large project several subprojects may be defined related to specific studies that have to be performed.
Subprojects are:
- RF evaporation of atoms in a magnetic trap
- Compression of atoms in a magnetic trap
- How to observe the transition to a condensate in triplet helium
- Theoretical investigation of a triplet helium condensate
- Investigation of trap loss processes
- Theoretical study of mixtures of helium-3 and helium-4
Atmospheric Physics
The research in the atmosphere group of the Space Research Organisation Netherlands (SRON) aims at determining and understanding the composition of the Earth's atmosphere using satellite remote sensing.
Detailed projects are:
- application of neural networks in radiative transfer modelling
- inelastic (Raman) scattering of solar light, Mg ions in the atmosphere
- greenhouse gases and ozone vertical distribution
- retrieval of water vapour from GOME
- validation of polarisation measurements
Rayleigh-Brillouin scattering in the Earth's Atmosphere
Currently our group is involved in performing a study for the European Space Agency (ESA) to characterize the Rayleigh-Brillouin scattering phenomenon in atmospheric molecules form an experimental perspective. A RB-scattering setup is under construction and measurements will be performed at 355 nm.
Supervisor: Wim Ubachs
Mode-locked diode lasers as frequency combs
Within the framework of the MEMPHIS-consortium our group is involved in the testing and development of miniature frequency comb lasers, based on diode-laser based mode-locked-laser systems. This work is in a collaboration with the Eindhoven University of Technology. In the near future it will become possible to conduct a research project in this field.
Supervisors: Kjeld Eikema and Wim Ubachs
