The first photoelectron band of difluorocarbene CF2, has been studied by threshold photoelectron (TPE) spectroscopy. CF2 was prepared by microwave discharge of a flowing mixture of hexafluoropropene, C3F6, and argon. A vibrationally resolved band was observed in which at least twenty-two components were observed. In the first PE band of CF2, the adiabatic ionization energy differs significantly from the vertical ionization energy because, for the ionization CF2 + (X˜ 2A1)+e ! CF2 (X˜ 1A1), there is an increase in theFCF bond angle (by 208) and a decrease in the CF bond length (by 0.7 ). The adiabatic component was not observed in the experimental TPE spectrum. However, on comparing this spectrum with an ab initio/Franck– Condon simulation of this band, using results from high-level ab initio calculations, the structure associated with thevibrational components could be assigned. This led to alignment of the experimental TPE spectrum and the computed Franck–Condon envelope, and a determination of the first adiabatic ionization energy of CF2 as (11.362 0.005) eV. From the assignment of the vibrational structure, values were obtained for the harmonic and fundamental frequencies of the symmetric stretching mode (n1’) and symmetric bending mode (n2’) in CF2 + (X˜ 2A1).
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|Titolo:||Difluorocarbene Studied with Threshold Photoelectron Spectroscopy (TPES): Measurement of the First Adiabatic Ionization Energy (AIE) of CF2|
|Data di pubblicazione:||2008|
|Appare nella tipologia:||01a Articolo in rivista|