Berlin 2014 – wissenschaftliches Programm

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SYCS: Symposium Electron dynamics in chiral systems

SYCS 2: Chiral Systems (contributed session by MO)

SYCS 2.6: Vortrag

Montag, 17. März 2014, 15:45–16:00, BEBEL HS213

Tracing photoinduced enantiomeric excess by femtosecond accumulative spectroscopy — •Andreas Steinbacher, Patrick Nuernberger, and Tobias Brixner — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

We utilize a fast and sensitive polarimeter [1], specifically designed for applications with femtosecond laser pulses, to follow the asymmetric photochemical conversion of a racemic mixture of 1,1’-binaphthyl-2,2’-diyl hydrogenphosphate. The photoreaction is initiated by circularly polarized UV laser pulses. Depending on the handedness of the polarization, more R- or S-enantiomers are gradually photodissociated, leading to a build-up of enantiomeric excess. Due to the sensitive accumulative detection scheme [1] with an interaction length of 250 µm and the measurement time set to 100 ms for a full determination of the optical activity, we are able to follow the dynamical evolution of this enantiomeric excess. For a specific illumination time, the enantiomeric excess is most pronounced, and decreases again for continued exposure to UV light, as a direct consequence of the different extinction coefficients of the enantiomers. Hence, this detection scheme gives rise to the possibility of employing it in quantum control applications in future experiments.

A. Steinbacher, J. Buback, P. Nuernberger, and T. Brixner, Opt. Express 20, 11838 (2012).