Resonance Fluorescence and Xenon Sensitization of the CO(A 1II→X 1Σ+) System

Abstract

Methods of excitation of the $\mathrm{CO}{\mathrm{(A}}^1\mathrm{\Pi )}$ system have been investigated, and it has been demonstrated that resonance fluorescence is an extremely efficient process. Even the very low intensity CO fourth‐positive ${\mathrm{(A}}^1\Pi \mathrm{\to }{X}^1{\Sigma }^{+})$ contaminant emission observed in rare‐gas resonance lamps gives strong fluorescence when minute amounts of CO are irradiated. It has been established that the Xe 1470‐Å resonance line does not produce $\mathrm{CO}{\mathrm{(A}}^1\mathrm{\Pi )}$ . On the other hand, Xe sensitization gives intense fourth‐positive emission by a collisional process involving the resonant $\mathrm{Xe}{(}^3{P}_1)$ state. Previous work had shown that three CO triplet states ${\mathrm{(d}}^3{\mathrm{\Delta ,\; e}}^3{\Sigma }^{-},\mathrm{and}{\mathrm{a\prime }}^3{\Sigma }^{+})$ are produced by Xe sensitization. Of the total singlet plus triplet emission, a fraction of 0.06 ± 0.15 is from the $A^1\Pi$ state.