Laser-induced fluorescence of the CHXCFO (X=F,Cl) radicals

Abstract

Laser-induced fluorescence spectra of the B̃←X̃ transition for three new halogen substituted vinoxy radicals were observed in the 306–333 nm region. The spectra of the trans- and cis-CHFCFO radicals were observed in the reactions of CHFCHF and CHFCF2 with atomic oxygen, and the spectrum of the cis-CHClCFO radical was observed in the reactions of CHClCHF and CHClCF2 with atomic oxygen. From an analysis of the laser-induced single vibronic level fluorescence, some of the vibrational frequencies could be determined for the ground electronic states (X̃); these frequencies are listed in Tables III and V. Some of the vibrational frequencies for the excited state (B̃) were also determined. These vibrational assignments are supported by ab initio calculations. The experimental results show that the electronic B̃←X̃ transition energy is increased by halogen atoms, especially by fluorine atoms at either the 1- or 2-positions. The C–C–O skeleton and the spectroscopic characteristics of trans-, cis-CHFCFO, and cis-CHClCFO are close to those of CH2CFO. It is suggested that the C–C–O skeleton of the vinoxy-type radicals is influenced more by the substitution of a halogen atom at the 1-position than at the 2-position.