Pressure dependence of isotopic enrichment in ozone formed by photolysis of oxygen

Abstract

Photolysis of molecular oxygen using ultra violet photons from Hg resonance lamp (184.95 nm and 253.65 nm) at different initial oxygen pressures (moderate to low pressure regime) was carried out. The formed ozone was analyzed and found to have isotopic enrichment more than about 95 %.. Depending upon the isotopic enrichment in ozone, the total pressure regime can be divided into three zones. From 600 torr to around 50 torr there is a steady increase in enrichment of ¹⁸O by about 25 %.. Below 50 torr the enrichment shoots up rapidly from a value of about 120 %. and reaches a peak value of 180 %. at around 18 torr. Below 18 torr the enrichment falls off dramatically by about 45-50 %. within a few torr of oxygen pressure. The three-isotope plot of oxygen yields a slope less than one indicating the importance of dissociation in the observed peak in the enrichment.