title: Reaction dynamics of a molecular switch unveiled by coherent two-dimensional electronic spectroscopy.
abstract: 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] (6,8-dinitro-BIPS), a photochromic system present in two ring-open forms differing in the cis/trans configuration of a double bond, which both undergo a photoinduced 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. This experiment demonstrates the potential of two-dimensional electronic spectroscopy for reactive processes.
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kullmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Ruetzel
authors.forename: Johannes
authors.initials: J
authors.lastname: Buback
authors.forename: Patrick
authors.initials: P
authors.lastname: Nuernberger
authors.forename: Tobias
authors.initials: T
authors.lastname: Brixner