Laser-induced fluorescence of the CD2CFO radical

Abstract

The laser-induced fluorescence spectrum of the B̃ 2A″→X̃ 2A″ transition of the CD2CFO radical has been observed in the region 316–335 nm. The radical was produced by 193 nm photolysis or by fluorine atom reaction with acetyl-d3 fluoride. The spectrum of CD2CFO was similar to that of CH2CFO reported previously except for small isotope shifts in the range 7–343 cm−1. The isotope shifts support the assignment of these spectra to fluorinated vinoxy radicals, and rule out the alternate assignment to FCO proposed by others. The X̃→B̃ electronic transition energy (T0) for CD2CFO was measured to be 29 867 cm−1, which is only 7 cm−1 lower than that for CH2CFO. From an analysis of the laser-induced single vibronic level fluorescence, some of the vibrational frequencies can be assigned for the ground electronic state; ν3(CO str.)=1735; ν4(CD2 sciss.)=1043; ν5(CF str.)=1248; ν6(CD2 rock.)=774; ν7(CC str.)=863; ν8(CCF bend)=597; and ν9(CCO bend)=370 cm−1. For the B̃ 2A″ state, ν3=1772; ν4=1073; ν5=1241; ν6=783; ν7=827; ν8=530; and ν9=370 cm−1. These assignments are supported by ab initio calculations. Among these fundamental frequencies, the ν4 and ν6 modes showed the largest isotope shifts, although isotope effects were observed in all the above vibrational fundamentals. The radiative lifetimes of the excited CD2CFO and the quantum yield of formation of the CH2CFO radical from photolysis of CH3CFO at 193 nm are also reported.