Darmstadt 2008 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 18: Femtosekundenspektroskopie
MO 18.10: Poster
Dienstag, 11. März 2008, 14:00–19:00, Poster C1
A Comparison of the Selective Excitation of Molecular Modes in Gas and Liquid Phase Using Femtosecond Pulse Shaping — •Abraham Scaria, Vinu Namboodiri, Jakow Konradi, and Arnulf Materny — Jacobs University Bremen, Germany
In our previous publications we have demonstrated that a selective excitation of specific vibrational modes in a molecule is possible by using a feedback-controlled optimization in a coherent-anti Stokes Raman scattering (CARS) process [1,2]. The mechanism behind the selective enhancement and suppression of vibrational modes is not clearly understood. The experiments suggest an important contribution by intermolecular dynamical processes. Here, it would be of importance to determine, what influence the interaction with surrounding molecules plays on the control result. In our contribution, we present results from optimal control experiments performed on CS2 molecules in the gas phase as well as in its liquid form. The CARS excitation was chosen to be not in resonance with an electronic transition in the molecule but to excite different vibrational modes coherently. A pure phase modulation of the Stokes pulse resulted in changes of the ratio of the Raman lines observed in the nonlinear scattering spectrum. This could also be achieved when no temporal shift between pump and Stokes laser resulted in a simple change of the Raman resonances. The differences between gas and liquid phase measurements will be discussed.
[1] J. Konradi, A.K. Singh, and A. Materny, PCCP 7, 3574 (2005).
J. Konradi, A. Scaria, V. Namboodiri, and A. Materny. J. Raman Spectrosc. 38, 1006 (2007).