Determination of the spectral dependences of the absolute quantum yields of O($^1$S) by the XeO$^*$ luminescence method. I. Photolysis of CO$_2$ and N$_2$O

A method is proposed for measuring the spectral distribution of the absolute quantum yield of $O(^1S)$ in the photolysis of oxygen-containing compounds $(RO)$. This involves investigating the luminescence excitation spectra of $XeO^*$ excimers formed in the $O(^1S)+Xe+Xe\rightleftarrows XeO^*+Xe$ reaction. The measurements were made in a following $RO-Xe$ mixture of accurately known composition in a system with differential evacuation. The spectral dependences of the quantum yield of $O(^1S)$ in the photolysis of $N_2O$ ($\lambda=170-102$ nm) and $CO_2$ ($\lambda=128-102$ nm) were obtained. The absorption spectra of these compounds and the excitation spectra of RO, corresponding to the transitions to states which dissociated forming $O(^1S)$, were determined. The mechanism for excitation and dissociation of $CO_2$ and $N_2O$ in these spectral ranges was discussed in the light of the experimental results and the published data. Transfer of the excitation energy from the $Xe$ atoms, formed by absorption of radiation in the spectral range $\lambda<120$ nm, to $N_2O$ molecules was observed, resulting in the dissociation of $N_2O$ to give $N_2(\widetilde X^1\Sigma_\varepsilon^+)$ and $O(^1S)$ or in the formation of $N_2$ and $XeO^*$.