Abstract
Photolysis of CO2 at 1849 Å (Hg lamp) has been studied at pressures in the range 66–800 psi, at room temperature. The primary dissociation quantum yield is 1.0, as determined by experiments in which the atomic oxygen product was scavenged in the form of O2. At high pressures (∼400 psi), O3 photolysis at 2537 Å gave appreciable CO3 formation by the reaction O(1D) + CO2 + M → CO3 + M, as evidenced by loss of O3. TO observe quantitative O3 production, it was therefore necessary to filter out the 2537 Å light. The products CO and O2 could not be recovered in 100% yield in most of the experiments. No satisfactory mechanism can be given for the product losses, although a number of possibilities can be ruled out. In particular, CO3 did not oxidize CO to CO2. The CO yield could be increased to nearly 100% by coating the cell walls with Kel-F grease, whereas the O2 yield simultaneously dropped to zero.
The quantum yield results at 1849 Å suggest that CO2 dissociates at all wavelengths where absorption is appreciable.
