Mainz 2017 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 8: Fast Intramolecular Dynamics
MO 8.4: Vortrag
Dienstag, 7. März 2017, 15:30–15:45, N 25
Femtosecond dynamics of the 2-methylallyl radical in the gas phase — •Anja Röder1, Ingo Fischer1, Roland Mitric1, Jens Petersen1, Kevin Issler1, Matthias Wohlgemuth1, and Lionel Poisson2 — 1University of Wuerzburg, Am Hubland Süd 97074 Wuerzburg, Germany — 2LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette, France
The methylated derivatives of the allyl radical(the 1-methylallyl or 2-methylallyl radical) are especially interesting for combustion chemistry, since biodiesel often contains branched or non-branched unsaturated fatty esters.
Produced via pyrolysis, the 2-methylallyl radical was examined using femtosecond pump-probe spectroscopy, with the pump laser wavelengths at 240 and 236 nm exciting into a p-state. The probe laser was the 800 nm fundamental of a Ti:Sapphire Laser. The lifetimes of these states were examined using time-resolved photoelectron spectroscopy (TRPES) or time-of-flight mass spectrometry (TOF-ms), showing two time-constants and considerable anisotropy in the photoelectron spectra.
Molecular-dynamic calculations using the field-induced surface hopping method coupled to DDFT reproduce well our experimentally result. The excited p-state decays faster than the time-resolution of the pump-laser to the 3s-state, which decays via the D1-state (first time constant) to the electronic ground state. (Second time constant) This assignment is further supported by the strong positive anisotropy in the photoelectron images, in agreement with ionization from an s-orbital.