Dissociative Excitation of Some Oxygen-Containing Molecules: Lifetimes and Electron-Impact Cross Sections

Abstract

Decay lifetimes of seven vacuum-ultraviolet O I and O II emission multiplets have been measured using a pulsed electron beam in low-pressure samples of ${\mathrm{O}}_2$, CO, NO, and ${\mathrm{H}}_2$O. The lifetimes and cascade patterns of the lines are consistent with known autoionization processes. In two cases, spin-orbit-induced autoionization rates are determined. Absolute electron excitation functions for 8447—Å O I have been measured in the above gases. Relative excitation functions for 1304-Å O I are normalized to the 8447-Å absolute cross section by means of a time-domain cascade analysis. A method for computing relative cross sections from $N$-exponential decays is outlined.