Berlin 2005 – scientific programme

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MO: Molekülphysik

MO 43: Ultrafast Processes

MO 43.9: Talk

Tuesday, March 8, 2005, 18:30–18:45, HU 2091

Photo-Rearrangement of o-Nitrobenzaldehyde Probed by Femtosecond Raman Spectroscopy — •Stefan Laimgruber, Wolfgang Schreier und Peter Gilch — Department für Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, D-80538 München, Germany

Aromatic nitro-compounds are known to photochemically abstract hydrogen atoms from adjacent hydrocarbon moieties. For ortho-substituted nitro-aromatics these abstractions proceed intra-molecularly and trigger secondary processes. Due to these processes aromatic nitro-compounds are used as, e.g., photo-labile protecting groups and as the leaving group in caged compounds. Here, we study a prototypical nitro-compound, o-nitrobenzaldehyde, which is photochemically transformed into o-nitrosobenzoic acid by a femtosecond stimulated Raman technique. This technique uses a white light continuum as the Stokes pulse in the stimulated Raman process. To our knowledge this is the first application of this technique for the investigation of photochemical processes. The transient Raman spectra obtained are compared with calculated spectra of possible intermediates and the mechanism of the reaction is discussed.