Time-of-Flight Spectroscopy of CO2 Photodissociation in the Vacuum Ultraviolet. Electron Emission from Cesium Surface by Metastable Singlet Oxygen Atoms

Time‐of‐flight spectroscopy has been employed in conjunction with metastable photofragment detection by electron emission from metal surfaces to study the photodissociation of CO₂ in the vacuum ultraviolet at wavelengths longer than 1050 Å. Irradiation was performed by unfiltered light. However, some wave‐length selection was provided by the CO₂ absorption itself and by choice of window material, LiF and CaF₂. The metastable detector was coated with cesium. The photodissociation, ${\mathrm{CO}}_2\mathrm{\hspace{0.17em}+\hspace{0.17em}h\upsilon \to }\mathrm{CO}{\mathrm{(X}}^1\mathrm{\Sigma )+}\mathrm{O}*$ , has been observed where O* can be $\mathrm{O}{(}^1\mathrm{S)}$ and/or $\mathrm{O}{(}^1\mathrm{D)}$ only. The result implies that the deactivation of metastable singlet oxygen atoms at a cesium surface produces electron emission. The analysis of the flight time distribution of O* shows that in the wavelength range from about 1160–1050 Å more than 50% of the dissociation leads to internally excited $\mathrm{CO}{\mathrm{(X}}^1\mathrm{\Sigma )}$ with considerable amounts of vibration‐rotation energy.