High-resolution spectroscopic study of the oxidation of white phosphorus

Abstract

The IR absorption spectra of the transient molecules PO, PO₂ and P₂O have been recorded at Doppler-limited resolution, using the O + P₄ chain reaction to generate them directly in a long-path flow cell. It was necessary to control the mixing conditions and the relative reactant concentrations carefully to observe these spectra, particularly the proportion of oxygen, since the spectrum of each oxide optimised under distinctly different conditions. While gas-phase spectra have previously been reported for PO and PO₂ the present work is the first to report spectroscopic detection of P₂O in the gas phase. A series of nearly equally spaced lines has been assigned to the P—O stretching mode of this transient molecule and supports the linear, non-symmetric structure (P—P—O) predicted theoretically.