Journal of Chemical Physics, Vol.121, No.14, 6861-6867, 2004
Laser-induced fluorescence of cyclohexadienyl (c-C6H7) radical in the gas phase
A laser-induced fluorescence spectrum was observed in the 500-560 nm region when a mixture of 1,4-cyclohexadiene and oxalyl chloride was photolyzed at 193 nm. The observed excitation spectrum was assigned to the (A) over tilde (2)A(2)<--(X) over tilde B-2(1) transition of the cyclohexadienyl radical c-C6H7, produced by abstraction of a hydrogen atom from 1,4-cyclohexadiene by Cl atoms. The origin of the (A) over tilde <--(X) over tilde transition of c-C6H7 was at 18 207 cm-1. From measurements of the dispersed fluorescence spectra and ab initio calculations, the frequencies of several vibrational modes in both the ground and excited states of c-C6H7 were determined: nu(5)(C-H in-plane bend)=1571, nu(8)(C-Hin-plane bend)=1174, nu(10)(C-C-C in-plane bend)=981, nu(12)(C-C-C in-plane bend)=559, nu(16)(C-C-C out-of-plane bend)=375, and nu(33)(C-C-C in-plane bend)=600 cm(-1) for the ground state and nu(8)=1118, nu(10)=967, nu(12)=502, nu(16)=172, and nu(33)=536 cm(-1) for the excited states. (C) 2004 American Institute of Physics.