Absolute chlorine atom quantum yield measurements in the UV and VUV gas-phase laser photolysis of CCl4

Absolute quantum yields ΦCl+Cl* for the formation of chlorine atoms were measured under collision-free conditions for the gas-phase dissociation of carbon tetrachloride (CCl4) after pulsed laser photoexcitation at 193 and 135 nm. By means of a photolytic calibration method, where the gas-phase photolysis of HCl was utilized as a reference, values of ΦCl+Cl* (193 nm)=1.5±0.1 and ΦCl+Cl* (135 nm)=1.9±0.1 could be obtained which demonstrate the importance of the ultraviolet (UV) and vacuum-UV photolysis of CCl4 as an efficient source of atomic chlorine formation.