Stuttgart 2012 – scientific programme

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MO: Fachverband Molekülphysik

MO 9: Femtosecond Spectroscopy II

MO 9.6: Talk

Tuesday, March 13, 2012, 12:00–12:15, V38.03

Reaction Dynamics of a Molecular Switch Unveiled by Coherent Two-Dimensional Electronic Spectroscopy — •Martin Kullmann, Stefan Ruetzel, Johannes Buback, Patrick Nuernberger, and Tobias Brixner — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Coherent two-dimensional electronic spectroscopy is usually employed on molecular species with fixed geometric configuration. Here we present two-dimensional Fourier-transform electronic spectra of dissolved 6,8-dinitro-1’,3’,3’-trimethylspiro[2H-1-benzopyran-2,2’-indoline], a photochromic system present in two ring-open forms which differ by a cis/trans configuration of a double bond. Both isomers undergo a photo-induced ring closure.

The two-dimensional spectra, recorded with 20 fs pump pulses centered at 605 nm and a supercontinuum probe covering the complete visible spectral range, allow for a detailed analysis of the photophysics and photochemistry of the two isomers, and directly reveal that cis/trans isomerization among them does not play a major role [1]. This experiment demonstrates the potential of two-dimensional electronic spectroscopy for reactive processes.

[1] M. Kullmann, S. Ruetzel, J. Buback, P. Nuernberger, and T. Brixner, J. Am. Chem. Soc. 133, 13074, (2011).