15min:

SHENG-GUI HE, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100080, P.R.C.; FUMIE X. SUNAHORI, JIE YANG AND DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.

The H₂As=O radical has been identified for the first time by laser-induced fluorescence (LIF) and single vibronic level (SVL) emission techniques. The radical was generated by a pulsed electric discharge in a mixture of AsH₃ and CO₂ and high-pressure argon and detected by observation of the B ²A' - X ²A' electronic transition in the 510-410 nm region. Moderate resolution LIF and SVL emission spectra of H₂AsO, D₂AsO, and HDAsO have been recorded and analysis shows unequivocally that the spectrum is due to the arsenyl radical. High-resolution spectra of the 0₀⁰ bands of H₂AsO and D₂AsO, which consist of strong a-type and weaker c-type transitions, revealed spin-splittings and small, but significant arsenic hyperfine splittings due to a Fermi contact interaction in the ground state. The effective molecular structures of H₂AsO in the ground and excited states have been determined from the rotational constants and will be discussed in the context of the analogous nitroxyl (X₂N=O) and phosphonyl (X₂P=O) radicals.