Berlin 2014 – scientific programme

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MO: Fachverband Molekülphysik

MO 21: Photochemistry

MO 21.1: Talk

Friday, March 21, 2014, 10:30–10:45, BEBEL HS213

The Photodissociation Dynamics of Fulvenallene, C7H6, Investigated by Velocity Map Imaging — •Jens Giegerich and Ingo Fischer — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland Süd, Würzburg

Fulvenallene is the most stable C7H6 isomer and is assumed to be an intermediate in the combustion of toluene. C7H6 has been observed in toluene rich flames and theoretical studies predict it to be the major decomposition product of the benzyl radical. It appears that fulvenallene is an important intermediate in oxidation and pyrolysis processes, which are relevant to the combustion of aromatic hydrocarbons and to the formation of PAH.

Fulvenallene was generated from phthalide as a precursor, which decomposes to the reactive intermediate in a vacuum jet flash pyrolysis source. The molecules were excited at around 247 nm. At this wavelength region the excited molecule dissociates to the fulvenallenyl radical C7H5 + H. The H-atom dissociation products were ionized in a [1+1'] REMPI process via the 1s-2p transition. The ionized H-atoms are recorded on a Velocity Map Imaging Detector. The observed translational energy distribution peaks around 0.06 eV. The expectation value for translational energy release lies at around 0.21 eV which accords to ~ 14% of the excess energy. The ionized H-atoms show an isotropic angular distribution, typical for statistical reactions. In addition time-delay scans were carried out. The time-delay scans show a rate with a time constant on the order of 150 ns and are in good agreement with RRKM predictions.