Production of 2537 Radiation and the Role of Metastable Atoms in an Argon-Mercury Discharge

Abstract

The average population of 6³P₁ mercury atoms is calculated from the measured 2537 output and resonance radiation diffusion theory. Average populations of 6³P_{2, 0} are then found by comparing the absorptions of 5461, 4358, and 4047. Populations for a 0.42‐amp. discharge in 3.5‐mm argon of high purity plus Hg vapor at 42°C in a tube 1½ inches in diameter are for 6³P_{2, 1, 0}, respectively, 7.6×10¹¹, 1.9×10¹¹, and 3.5×10¹¹ cm⁻³; these are ⅕, 1/20, and ⅕ of the corresponding Boltzmann populations, for the electron temperature of 11,100°K. Rates of collisions of the first and second kinds involving electrons (average concentration 2.1×10¹¹ cm⁻³), and the 6¹S₀ and 6³P_{2, 1, 0} states are calculated using known excitation functions and detailed balancing. The results predict populations for 6³P_{2, 1, 0} within 10 percent of those observed; they further predict that ⅔ of the observed 2537, ⅔ of the visible triplet, and ¾ of the 3650 group are produced stepwise via 6³P. Quenching collisions involving argon are assumed negligible. The results account fairly well for the maximum in the 2537 versus Hg pressure curve, for the decrease in the 2537 output efficiency with increasing current, and for the decrease in electron temperature which is associated with both these effects.