Düsseldorf 2007 – scientific programme

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MO: Fachverband Molekülphysik

MO 61: Quantum Control I

MO 61.8: Talk

Friday, March 23, 2007, 12:15–12:30, 6F

Single-beam Heterodyne CARS for Sensitive Chemically Selective Microscopy — •Bernhard von Vacano, Tiago Buckup, and Marcus Motzkus — Physikalische Chemie, Philipps-Universität Marburg, D-35032 Marburg, Germany

With shaped femtosecond laser pulses, coherent anti-Stokes Raman-scattering (CARS) microspectroscopy can be accomplished in a straight-forward single-beam approach. To increase the sensitivity, we introduce interferometric detection in a very simple experimental extension: in addition to the optical fields driving the CARS process, a controllable local oscillator is derived by pulse-shaping of a single femtosecond laser beam. The heterodyne detected signal can be amplified by more than three orders of magnitude and shows linear concentration dependence. Like this, the sensitivity of chemically selective CARS detection can be increased dramatically, without adding complexity to the single-beam setup. As an example, we show sensitive and chemically selective detection of down to 8×10⁶ analyte molecules.