Broadband UV-Vis vibrational coherence spectrometer based on a hollow fiber compressor

We describe abroadband transientabsorption (TA) spectrometer devised to excite and probe, in the blue to UV range, vibrationalcoherencedynamics in organic molecules in condensed phase. A 800-nm Ti:Sa amplifier and a hollow fiber compressor are used to generate a 6-fs short pulse at 1 kHz.Broadband sum frequency generation with the fundamental pulse is implemented to produce a 400-nm, 8-fs Fourier limited short pulse. A UV-Vis white-light supercontinuum is implemented as a probe with intensity self-referencing to achieve a shot-noise-limited sensitivity. Rapid scanning of the pump-probe delay is shown very efficient in suppressing the noise resulting from low-frequency pump intensity fluctuations. Using either of the 800-nm or 400-nmbroadband pulses as the pump for TAspectroscopy of organic molecules in solution, we resolve oscillatory signals down to the 320 nm probing wavelength with a 3200 cm−1 FWHM bandwidth. Their Fourier transformation reveals the corresponding molecular vibrationalspectra. Finally, we demonstrate the use of this setup as a vibrationalcoherence spectrometer for the investigation of the vibrationaldynamics accompanying the sub-ps C=C photoisomerization of a retinal-like molecular switch through a conical intersection.

Source: Review of Scientific Instruments - September 20, 2016 Category: Physics Authors: Moussa Gueye, Julien Nillon, Olivier Cr égut and Jérémie Léonard Source Type: research