Düsseldorf 2007 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 21: Femtosecond Spectroscopy II
MO 21.3: Vortrag
Dienstag, 20. März 2007, 11:15–11:30, 6D
Femtosecond vibrational sum frequency generation in the fingerprint region — •Sylvie Roke — MPI for Metals Research, Heisenbergstrasse 3, 70569 Stuttgart, Germany
Second-order nonlinear optical techniques are well established tools to study interfaces. Infrared visible Sum Frequency Generation (SFG) is an extremely valuable tool, since it combines the surface specificity with the ability to probe vibrational degrees of freedom. When using femtosecond lasers one can access both structure and dynamics of the interface.
Such studies have been limited, however, by the availability of femtosecond infrared laser sources. Therefore, most femtosecond SFG studies (as well as most other femtosecond tecniques that employ infrared radiation) have been performed in the frequency region of 4000-1000 cm−1.
The fingerprint region (1000-500 cm−1) is a very interesting one since this region contains typically vibrational modes that are specific to the 3D-structure of molecules, and is very sensitive to molecular interactions. This has remained unexplored. Therefore, we report a table-top femtosecond Ti:Sa laser that produces high power laser pulses, which are converted into tunable infrared radiation. The system produces infrared pulses with a tuning range from 4000-500 cm−1 and a power of 110-11 mW. We also show it is possible to probe surface vibrational modes in the fingerprint region, with a femtosecond SFG experiment.