LASER-INDUCED FLUORESCENCE IN THE B-APPROXIMATELY-X-APPROXIMATELY SYSTEM OF THE HCO RADICAL

The spectroscopy of the B̃2A′-X̃ 2A′ system of the formyl radical has been studied by laser-induced fluorescence. HCO was generated byphptolysis of acetaldehyde, and a tunable laser operated near 245 nm excited eight bands of B̃-X̃. The (0,0,2)-(0,0,0) band has been rotationally analyzed, yielding A′ = 14.46cm-1 and (B′ + C′)/2 = 1.13 cm-1 for this slightly asymmetric top; asymmetry splitting and spin doubling are observed. The intense branches have ΔK = 0 but there also are weaker perpendicular components with the transition moment near the b axis. Vibronic transition energies agree with those from matrix absorption but with a 130 cm -1 blueshift. Resolved fluorescence spectra to X̃ levels as high as 1S 000 cm -1 furnish vibrational constants for the ground state. © 1990 American Institute of Physics.