Relaxation of 6 2P3/2 metastable and 6 2P1/2 ground state atomic thallium produced in the photodissociation of thallium halide vapors at high densities

Abstract

Decay rates of the 6 2P3/2 metastable and 6 2P1/2 ground state atomic thallium densities produced in UV photodissociation (at λ193, 222, 249, 308, and 353 nm) of TlI, TlBr, and TlCl molecular vapors have been measured for vapor densities from 1013 to 1017 cm−3. Dominant relaxation processes have been identified as (i) for the metastable state, collisional deexcitation by thallium halide molecules at high halide densities (≥1015 cm−3) and by free halogens and trace impurities at lower halide densities and (ii) for the ground state, diffusion in the ambient (argon/thallium halide) gas at high halide densities and volume reassociation under certain conditions at low halide densities. Cross sections and diffusion coefficients are evaluated.