Photolysis of CO2 in Far Ultraviolet

Abstract

The photolysis of CO2 in both static and flow systems at 1470 and 1236 Å, from room temperature up to 100°C, shows CO/O2 ratios decreasing with increasing pressure of CO2, leveling off at a value ∼5, which is then independent of both temperature and pressure. The data, obtained by mass-spectral analysis of the products after unreacted CO2 had been condensed, show no evidence of masses greater than 44. Infrared spectra show no evidence of CO3 in the gas phase even when the products were condensed on solid CO2. It is shown that CO2 can be slowly desorbed by pumping from a reaction vessel in which CO2 has been photolyzed and, if heated, H2O. It is proposed that the reaction: O(1D)+H2O(ads)→2OH(ads) occurs on the walls and that CO2 is adsorbed on OH(ads) yielding a surface bicarbonate radical HCO3(ads). It is suggested that this species could be that currently considered to be CO3.