Düsseldorf 2007 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 56: Poster: Femtosecond Spectroscopy

MO 56.7: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster A

Optimal Control of CARS Spectra with Tailored Femtosecond Laser Pulses: Theory and Experiment — •Jakow Konradi, Soroosh Pezeshki, Jörg Liebers, Abraham Scaria, Vinu Namboodiri, Ulrich Kleinekathöfer, and Arnulf Materny — International University Bremen (Jacobs University Bremen as of spring 2007), Germany

The goal of coherent control in femtosecond spectroscopy is the preparation of desired quantum states of a molecule. Here, the most versatile approach is the use of suitably shaped excitation fields. In order to provide the correct pulse shapes, an exact knowledge of the molecular Hamiltonian is required, which in most cases is not available. An experimental way to solve this problem is the use of feedback-controlled learning-loop techniques. Recently, we have demonstrated the application of such an optimal control scheme for the selective excitation of vibrational modes in femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS). Here, the femtosecond laser pulses were shaped in a 4f-arrangement by means of phase and amplitude modulation guided by an evolutionary algorithm. The ratio of the mode intensities in the nonlinear spectrum served as feedback for the optimization. In our contribution we are presenting the optimal control of the femtosecond CARS spectrum of iodine. The experimental results are compared with theoretical calculations. For a simulation of the anti-Stokes spectra, the experimentally found pulse shapes were employed.