Infrared (0.9ndash;1.65 mgr;m) emission from thallium iodide photoexcited with ultraviolet excimer laser radiation

摘要

The infrared emission spectra from 0.9 to 1.65 mgr;m produced when thallium iodide vapor is photodissociated by excimer laser wavelengths of 193, 248, 308, and 351 nm are reported. In this spectral region, only atomic thallium transitions were observed. No emission from metastable atomic iodine at 1.315 mgr;m (5thinsp;2P1/2rarr;5thinsp;2P3/2) or thallium at 1.283 mgr;m (6thinsp;2P3/2rarr;6thinsp;2P1/2) was ever detected in contrast to strong 1.315 mgr;m signals obtained by ultraviolet (UV) excimer laser dissociation of C3F7I. The failure to detect metastable atomic emission from TlI photodissociation is explained by the fast quenching of the metastable states during superelastic collision with electrons produced by photoionization of the TlI. Consequently, a pulsed iodine 1.315 mgr;m laser based on photodissociation of thallium iodide does not seem practical.