title: Multidimensional spectroscopy of photoreactivity.
abstract: Coherent multidimensional electronic spectroscopy is commonly used to investigate photophysical phenomena such as light harvesting in photosynthesis in which the system returns back to its ground state after energy transfer. By contrast, we introduce multidimensional spectroscopy to study ultrafast photochemical processes in which the investigated molecule changes permanently. Exemplarily, the emergence in 2D and 3D spectra of a cross-peak between reactant and product reveals the cis-trans photoisomerization of merocyanine isomers. These compounds have applications in organic photovoltaics and optical data storage. Cross-peak oscillations originate from a vibrational wave packet in the electronically excited state of the photoproduct. This concept isolates the isomerization dynamics along different vibrational coordinates assigned by quantum-chemical calculations, and is applicable to determine chemical dynamics in complex photoreactive networks.
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Center for Nanosystems Chemistry (CNC), and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, 97074 Würzburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Ruetzel
authors.forename: Meike
authors.initials: M
authors.lastname: Diekmann
authors.forename: Patrick
authors.initials: P
authors.lastname: Nuernberger
authors.forename: Christof
authors.initials: C
authors.lastname: Walter
authors.forename: Bernd
authors.initials: B
authors.lastname: Engels
authors.forename: Tobias
authors.initials: T
authors.lastname: Brixner
keywords: 2D spectroscopy; photoreactive processes; ultrafast spectroscopy; vibrational coherence