Mainz 2017 – scientific programme

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MO: Fachverband Molekülphysik

MO 12: Posters 2: Molecular Dynamics, Clusters, and High Resolution Spectroscopy

MO 12.5: Poster

Wednesday, March 8, 2017, 17:00–19:00, P OG1

Collinear Phase-modulated Femtosecond Pump-Probe Experiments Using a Low Repetition-rate Laser System — •Marcel Binz, Lukas Bruder, Ulrich Bangert, and Frank Stienkemeier — Institute of Physics, University of Freiburg, Germany

A particularly robust and very versatile stabilization method for coherent time-resolved spectroscopy is the phase-modulation approach [1], [2]. The combination of continuous acousto-optical phase-modulation with lock-in detection greatly improves the signal-to-noise ratio and the sensitivity in this scheme. However, the method was thought to be suitable only for high repetition-rate laser systems ( 200kHz) which are not available in many labs.

Recently, we have successfully implemented this technique in a pump-probe scheme with fs laser pulses at 5kHz repetition-rate. We found that much higher modulation frequencies than laser repetition-rates can be used without losing performance. This effect, which we call phase-synchronous undersampling, shows promise for the implementation of the phase-modulation scheme in even lower repetition-rate XUV laser sources by shifting the carrier frequency far away from the low frequency noise spectrum.

[1] P. F. Tekavec, T. R. Dyke, and A. H. Marcus, J. Chem. Phys. 125, 194303 (2006).

[2] L. Bruder, M. Mudrich, and F. Stienkemeier, Phys. Chem. Chem. Phys. 17, 23877 (2015).