EXCITED-STATE DYNAMICS OF CH2CHO ((B)OVER-TILDE(2)A'')

State-specific radiative lifetimes and electronic quenching cross sect ions are reported for four different vibrational modes of CH2CHO ((B) over tilde(2)A''). Ground-state vinery radicals are produced by 193-nm excimer laser photolysis of CH3OCH=CH2, and pumped to the (B) over ti lde state by a tunable dye laser operating between 332 and 348 nm. Flu orescence decay rates are determined in the presence of 12 collision p artners: He, Ar, N-2, O-2, CO, H-2, HCl, N2O, CO2, C2H4, CH3OCH=CH2, a nd SF6. The measured electronic quenching cross sections vary from 0.0 1 to 66.5 Angstrom(2). Zero pressure radiative lifetimes are found to vary from 98 +/- 10 to 154 +/- 18 ns, depending on the vibrational mod e. Possible mechanisms for lifetime shortening and collisional quenchi ng are discussed.