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Predissociation mechanism and spin-rotation constant of the HCO B{sup 2}A{prime} state

Conference ·
OSTI ID:456884
;  [1]
  1. National Tsing Hua Univ., Hsinchu, Tawain (China)
Formyl radicals produced from photolysis of acetaldehyde at 310 nm were supersonically cooled and detected via the transition using the laser-induced fluorescence (LIF) technique. Spectra at resolution 0.16 cm{sup -1} and fluorescence lifetimes of HCO B (0,0,0), (0,0,1) and (0,1,0) levels were measured. The observed lifetimes decrease rapidly with variation of the rotational quantum number K{sub a} from 0 to 2 but slowly with the rotational quantum number N from 0 to 8. Experimental data indicate that the b state is coupled to a predissociating state via an {alpha}-type Coriolis interaction, to account for the rotationally dependent lifetime for the low vibrational levels of the HCO B state. Correction of the fluorescence quantum yield for individual rotational states is necessary to obtain accurate ground state populations by LIF when using the B-X transitions. The intensity distribution of the two spin states observed implies a negative value of the spin-rotation parameter for the B state, in contrast with the ground electronic state.
OSTI ID:
456884
Report Number(s):
CONF-9506113--
Country of Publication:
United States
Language:
English