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.