Premium
Difluorocarbene Studied with Threshold Photoelectron Spectroscopy (TPES): Measurement of the First Adiabatic Ionization Energy (AIE) of CF 2
Author(s) -
Innocenti Fabrizio,
Eypper Marie,
Lee Edmond P. F.,
Stranges Stefano,
Mok Daniel K. W.,
Chau Footim,
King George C.,
Dyke John M.
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801699
Subject(s) - ionization energy , ionization , atomic physics , adiabatic process , photoemission spectroscopy , ab initio , x ray photoelectron spectroscopy , ab initio quantum chemistry methods , bond length , chemistry , materials science , physics , ion , nuclear magnetic resonance , crystallography , molecule , organic chemistry , thermodynamics , crystal structure
Abstract The first photoelectron band of difluorocarbene CF 2 , has been studied by threshold photoelectron (TPE) spectroscopy. CF 2 was prepared by microwave discharge of a flowing mixture of hexafluoropropene, C 3 F 6 , and argon. A vibrationally resolved band was observed in which at least twenty‐two components were observed. In the first PE band of CF 2 , the adiabatic ionization energy differs significantly from the vertical ionization energy because, for the ionization CF 2 + (X̃ 2 A 1 )+e − ← CF 2 (X̃ 1 A 1 ), there is an increase in the FCF bond angle (by ≈20°) and a decrease in the CF bond length (by ≈0.7 Å). 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 the vibrational 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 CF 2 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 ( ν 1 ′) and symmetric bending mode ( ν 2 ′) in CF 2 + (X̃ 2 A 1 ).