Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 34: Photochemistry

MO 34.9: Talk

Friday, March 18, 2011, 12:30–12:45, TOE 317

Precise and rapid detection of optical activity for femtosecond spectroscopy — •Andreas Steinbacher, Johannes Buback, Patrick Nuernberger, and Tobias Brixner — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg

We introduce polarimetry, i.e. the detection of optical rotation of light polarization, in a configuration that is suitable for femtosecond spectroscopy. The polarimeter is based on the common-path optical heterodyne interferometry method and provides fast and highly sensitive detection of rotating power. Femtosecond pump and polarimeter probe beams are integrated into a recently developed accumulative technique that further enhances sensitivity with respect to single-pulse methods. The high speed of the polarimeter affords optical rotation detection during the pump-pulse illumination period of a few seconds. We illustrate the concept on the photodissociation of the chiral enantiomers of methyl p-tolyl sulfoxide. The sensitivity of rotatory detection, i.e. the minimum rotation angle that can be measured, is determined experimentally including all noise sources to be 0.10 milli-degrees for a measurement time of only one second and an interaction length of 250 µm.