Berlin 2001 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 10: Ultrafast Spectroscopy
CPP 10.6: Talk
Thursday, April 5, 2001, 17:25–17:45, 110
Orientation and vibrational relaxation of acetonitrile at the yttrium aluminum garnet interface observed by sumfrequency spectroscopy — •Martin Saß, Michael Lettenberger, and Alfred Laubereau — Technische Universität München, Physik-Department E11, James-Franck-Straße, 85748 Garching
Acetonitrile at the interface to yttrium aluminum garnet (YAG) is studied by IR-excitation sum-frequency (SF) spectroscopy. Using two independently tunable infrared pulses in combination with a visible upconversion pulse for the SF-probing process, a time-resolved vibrational spectroscopy is accomplished. Rapid energy transfer between the CH-stretching modes is observed with a time constant of 1.8 ± 1.0 ps. The population relaxation of the CH3-stretching modes is found to be bimodal with a decay time of T1 = 5.9 ± 1.8 ps, while the ground state is re-populated rather slowly with 150 ± 50 ps. Furthermore SF spectroscopy provides information on the orientation of the acetronitrile molecules at the interface. For this investigation additional spectra in the region of the CN-stretch are measured.