Scannable picosecond UV laser system for resonance Raman spectroscopy

We propose to assemble a new scannable picosecond laser system for resonance Raman spectroscopy (RRS) studies at the Biomolecular Analysis and Spectroscopy (BAS) group of the Laser Centre Vrije Universiteit Amsterdam. RRS a widely applicable and highly selective molecular vibration spectroscopy mode, suitable for non-invasive, in situ characterization of a wide range of chemical and biological systems, including aqueous ones. It has been amply demonstrated in the recent literature and also by our group that RRS offers important advantages over conventional Raman spectroscopy: orders of magnitude higher sensitivity and strongly improved selectivity over non-relevant matrix components. Potential interference from fluorescence can be overcome by applying pulsed laser excitation and fast-gated detection. However, the potential of RRS has so far not been thoroughly explored for lack of a suitable excitation source, which is essential for optimum resonance enhancement. The new scannable picosecond laser system, for which the necessary components have recently become available, would provide wavelength flexibility over the 210 - 495 nm range. The 15 ps pulse length is ideal for RRS: it can be combined with fluorescence rejection, while being long enough to avoid significant spectral bandbroadening. Autotracking electronics will enable quick wavelength adjustment and even automated scanning. Once completed, the superior wavelength flexibility and spectral resolution of the setup will enable us to pursue the following new research projects: " RRS studies on ligand-receptor interactions (e.g., the H1 histamine receptor) at selective excitation wavelengths, which may provide more detailed information than earlier fluorescence studies. " RRS studies of heme proteins, with emphasis on the effects of ligands on the Raman excitation profile (REP) of the porphyrin Soret band. " RRS studies on nucleic acids and their derivatives using deep UV excitation. " Fundamental studies of REPs of small molecules in order to better understand and predict excited-state resonance enhancement processes; in collaboration with theoretical chemistry. " Depth profiling through non-transparent media based on gated detection of slowly migrating photons. In addition, we expect that this unique instrument will also be very attractive to external users from Dutch institutes, private companies, and international research groups.