15min:

ROBERT A. GRIMMINGER AND DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY, 40506-0055.

The A²A₁ - X²B₁ electronic band system of the AsD₂ and AsHD free radicals has been observed by laser induced fluorescence (LIF) spectroscopy. AsD₂ (or AsHD) was produced in a pulsed supersonic expansion by electric discharge dissociation of a mixture of 5% AsD₃ (or AsH_xD_3-x mixture) seeded in argon. Single vibronic level emission spectra have been obtained for both AsD₂ and AsHD. The observed LIF transitions of AsD₂ in the 411 - 505 nm region exhibit a long progression in the excited state bending vibration. High-resolution rotationally resolved spectra of the 0⁰₀ band of AsD₂ were also recorded. This alicc-type band shows prominent K_a = \pm 3 transitions due to the large change in the asymmetry parameter upon electronic excitation. Extensive hyperfine splittings were resolved which allowed the determination of the excited state Fermi contact parameter. The data have been used to refine the molecular structure of the AsH₂ radical.