Thresholds of photolysis of O2 and of formation of O3 from O2 dispersed in solid neon

Irradiation of O-2 dispersed in solid Ne with ultraviolet light produced infrared absorption lines of O-3 and emission lines from atomic O (D-1(2) P-3(1,2)), molecular O-2 (A (3)(u) X (3)sigma(g)) and radical OH (A (2)sigma(+) X (2)(I)) in the visible and near-ultraviolet regions. The threshold wavelength for the formation of O-3 was determined to be 200 +/- 4 nm, corresponding to energy 6.20 +/- 0.12 eV, which is hence the threshold for dissociation of O-2. The thresholds of emission from excited O (D-1(2)), O-2 (A (3)(u)) and OH (A (2)sigma(+)) were all observed to be 200 +/- 4 nm, the same as for the formation of O-3 in this photochemical system. The results indicate that, once O-3 was generated, it was readily photolyzed to produce the long-lived atom O (D-1(2)). Further reactions of O (D-1(2)) with O-3 produced excited O-2 (A (3)(u)); reaction with water yielded radical OH (A (2)sigma(+)). These results enhance our understanding of the evolution of the transformation of oxygen and open a window for the understanding of complicated processes in the solid phase.