THE ELECTRONIC SPECTRUM OF H$_2$PO, THE PROTOTYPICAL PHOSPHORYL FREE RADICAL

Author Institution: Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055The electronic spectrum of the H$_2$PO radical has been identified by laser-induced fluorescence (LIF) and single vibronic level (SVL) emission techniques. The radical was produced in a pulsed electric discharge jet using a precursor mixture of phosphine (PH$_3$) and carbon dioxide in high-pressure argon and the $\tilde{B}$$^2$A$^{\prime}$ - $\tilde{X}$$^2$A$^{\prime}$ electronic transition was detected in the 410-338 nm region. Low resolution LIF and SVL emission spectra of H$_2$PO and D$_2$PO have been recorded and the $a^{\prime}$ vibrational frequencies have been determined in both states. High-resolution spectra of the 0$_0^0$ bands of H$_2$PO and D$_2$PO, which consist of strong $a$-type and weaker $c$-type components, were recorded. The spectra have been rotationally analyzed and the excited state molecular structure determined. The spectrum of H$_2$PO will be discussed in comparison with the spectra of other phosphoryl and arsenyl radicals that have been recently studied in our laboratory