Laser-induced fluorescence of the CHClCHO radical and reaction of oxygen atoms with halogenated ethylenes

A new laser-induced fluorescence spectrum has been observed in the region 3 20-360 Dm. Since this spectrum is observed when reacting oxygen atoms with chlorinated ethylenes such as CH2CHCl, CH2CCl2, CHClCHCl, and CHClCHF and a lso when chlorine atoms react with chloroacetaldehyde, the fluorescing mole cules are identified as cis- and trans-2 chlorovinoxy radicals (cis- and tr ans-CHClCHO). From an analysis of the laser-induced single vibronic level f luorescence, some of the vibrational frequencies can be assigned for the gr ound electronic state ((X) over tilde (2)A "): nu (3)(CO str) = 1567, nu (4 )(CH rock.) = 1380, nu (5)(CH rock.) = 1309, nu (6)(CC str) = 1060, nu (7)( CCl str) = 820, nu (8)(CCO bend.) = 677, and nu (9)(CCCl bend.) = 220 cm(-1 ) for cis-CHClCHO; nu (3) = 1581, nu (4) = 1379, nu (5) = 1267, nu (6) = 11 45, nu (7) = 942, nu (8) = 472, and nu (9) = 324 cm(-1) for trans-CHClCHO. Some of the vibrational frequencies for the excited (B) over tilde (2)A " s tate also are assigned. These vibrational assignments are supported by ab i nitio calculations. The calculated geometries of the cis- and trans-CHClCHO radicals are planar in the ground state and slightly nonplanar in the exci ted state. Radiative lifetimes of the excited cis- and trans-CHClCHO radica ls are also reported. The experimental results showed that the C-C-O skelet on and spectroscopic character of the cis- and trans-CHClCHO are closer to those of CH2CHO than to those of CH2CFO. The mechanisms of the O + halogena ted ethylene reactions are discussed.