The Raman effect is inelastic scattering of laser light at specific frequencies corresponding to the energy levels of the ground state of a molecule. Our group develops new methods for advanced Raman spectroscopic detection.
Stimulated Raman Scattering microscopy
Stimulated Raman Scattering microscopy allows non-invasive label-free optical imaging with high sensitivity and molecular specificity. Over the last few years, we have developed a flexible imaging set-up and are now focusing on biomedical applications.
Image: 3D rendering of a mouse neuron with SRS signal originating from proteins. The protein-filled nucleus is clearly identifiable.
Projects include investigations of adipocytes in zebrafish, visualizing neurotransmitters by stable isotope labeling and improvement of tissue penetration by employing longer wavelengths.
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Raman spectroscopy for the detection of extraterrestrial life
We work on improving Raman spectroscopy methods to help detect extraterrestrial life. The prime candidate in the search for life is Mars. Because of Mars’ extreme surface conditions, only extremophile organisms would be capable of surviving there. These organisms are likely to ‘hide’ slightly underneath the surface, reducing the UV-radiation levels such that life is sustainable. To detect these bacteria through the thick mineral layer, it is useful to have some depth selectivity.
Using time-resolved Raman we can create this depth selectivity. This technique uses a pulsed laser and a time-gated CCD camera. Then, when measuring in backscattering detection, light that arrives at the detector later, originates from deeper layers in the sample. This allows us to separate signals from deeper layers and therefore improve the chances we would detect life that is hidden below a layer that gives strong signal.
We are also working on developing Raman imaging set-ups to make more efficient use of our CCD detectors and thereby make measurements quicker and more efficient.