Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 14: Poster 2: Biomolecules, Electronic Spectroscopy, Experimental Techniques, Quantum Chemistry, Various Topics

MO 14.18: Poster

Mittwoch, 14. März 2012, 16:30–19:00, Poster.IV

Single-beam-CARS using broadband shaped laser pulses — •Alexander Wipfler, Jean Rehbinder, Tiago Buckup, and Marcus Motzkus — Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany

CARS microscopy has proven to be a powerful tool for the imaging of biological and chemical samples. In single-beam-CARS experiments all photons involved in the signal generation stem from one laser pulse which decreases the experimental demands. As the accessible Raman range is limited by the excitation bandwidth, short pulses with broad spectra are desirable. Therefore special care has to be taken in pulse compression. We present a new single-beam-setup using a light source consisting of no more than a commercial sub-10fs-Ti:Sa-oscillator and a pulse shaper that is able to detect the entire relevant vibrational Raman spectrum from the fingerprint up to the CH-stretching region. As one excitation scheme, the control of the Raman excitation is presented in theory and demonstrated experimentally on neat liquid samples. Another approach is the multiplexing of single-beam-CARS by the introduction of a narrowband feature in the excitation spectrum. This is demonstrated in chemical selective imaging of moss cells and in the full determination of the third-order nonlinear susceptibility.