| Autor: |
Hirsch F; Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany., Fischer I; Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany., Bakels S; Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands., Rijs AM; Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands. |
| Abstrakt: |
Resonance-stabilized radicals are considered as possible intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs) in interstellar space. Here, we investigate the fulvenallenyl radical, the most stable C 7 H 5 isomer by IR/UV ion dip spectroscopy employing free electron laser radiation in the mid-infrared region between 550 and 1750 cm -1 . The radical is generated by pyrolysis from phthalide. Various jet-cooled reaction products are identified by their mass-selective IR spectra in the fingerprint region, based on a comparison with computed spectra. Interestingly, benzyl is present as a second resonance-stabilized radical. It is connected to fulvenallenyl by a sequence of two H atom losses or additions. Among the identified aromatic hydrocarbons are toluene and styrene, as well as polycyclic molecules, such as indene, naphthalene, fluorene and phenanthrene. Mechanisms for the formation of PAH from C 7 H 5 have already been suggested in previous computational work. In particular, the radical/radical reaction of two fulvenallenyl radicals provides an efficient route to phenanthrene in one bimolecular step and might be relevant for PAH formation under astrochemical conditions. |
