Experimental Determination of the Excitation Transfer Cross Section from the6P13and6P03States of Mercury to Thallium

The excitation transfer cross sections to several of the excited states of thallium from the $6{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ and $6{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ states of mercury have been obtained at various temperatures in the range 800°C to 900°C. Analysis of the equilibrium rates of absorption, emission, and collision processes allows the calculation of excitation transfer cross sections from experimentally determined ratios of intensities of thallium-sensitized fluorescence lines to the intensity of mercury resonance fluorescence, using calculated values of the thallium transition probabilities. The values obtained for the excitation transfer cross sections are comparable in magnitude with collision cross sections based on considerations of gas kinetics.