Cross Sections for the Collision of Thallium (62 P1/2 and 62 P3/2) with I2

Abstract

The inelastic collision cross sections with I₂ have been measured for the ground state (6²P_1/2) and the metastable state (6²P_3/2) of thallium. The thallium atoms were produced in the presence of a known amount of I₂ by photodissociating TlI salt vapor with a short pulse of uv light. The cross sections were computed from the decay rate of the thallium density. We have observed that the collision of the metastable state with I₂ results in the de‐excitation of the state rather than in chemical reaction. The cross section for the process $\mathrm{Tl}{\text{(6}}^2{P}_{\text{1/2}}\mathrm{)+}{\mathrm{I}}_2\to \mathrm{TlI}+\mathrm{I}$ is 105 Ų and for the process $\mathrm{Tl}{\text{(6}}^2{P}_{\text{3/2}}\mathrm{)+}{\mathrm{I}}_2\to \mathrm{Tl}{\text{(6}}^2{P}_{\text{1/2}}\mathrm{)+}{\mathrm{I}}_2$ is 159 Ų. these results are in good agreement with theory.