THE ELECTRONIC SPECTRUM AND MOLECULAR STRUCTURE OF THE ARSENYL (H$_2$As=O) FREE RADICAL
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Date
2009
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Publisher
Ohio State University
Abstract
The H$_2$As=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 AsH$_3$ and CO$_2$ and high-pressure argon and detected by observation of the $\tilde{B} ^2{A}^{\prime} - \tilde{X} ^2{A}^{\prime}$ electronic transition in the 510-410 nm region. Moderate resolution LIF and SVL emission spectra of H$_2$AsO, D$_2$AsO, and HDAsO have been recorded and analysis shows unequivocally that the spectrum is due to the arsenyl radical. High-resolution spectra of the $0_0^0$ bands of H$_2$AsO and D$_2$AsO, 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 H$_2$AsO in the ground and excited states have been determined from the rotational constants and will be discussed in the context of the analogous nitroxyl (X$_2$N=O) and phosphonyl (X$_2$P=O) radicals.
Description
Author Institution: Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100080, P.R.C.; Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055