The Quenching of Mercury Resonance Radiation by Hydrogen, Carbon Monoxide and Nitrogen

An investigation was made of the dependence upon the temperature of the quenching of mercury resonance radiation by hydrogen, carbon monoxide and nitrogen. The quenching by hydrogen was effectively independent of the temperature from 473°K to 973°K, but that by carbon monoxide and by nitrogen decreased with increasing temperature. This decrease was somewhat more marked in nitrogen than in carbon monoxide. These results show that the metastable $2{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ state of the mercury atom is involved in the quenching by carbon monoxide and by nitrogen, but not appreciably in the quenching by hydrogen. The quenching by hydrogen may be accounted for by a reaction involving the dissociation of the hydrogen molecule by collision with a $2{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ mercury atom, followed in a certain small fraction of the cases by the probable excitation by collision with a second $2{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ atom of the mercury hydride molecule so produced. The effective cross sections for energy transfer in the first process at the different temperatures are given. The quenching by carbon monoxide and by nitrogen may be accounted for by the transition $2{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}\to 2{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ of the mercury atoms at gas collisions, by the return of some of the $2{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ atoms to the $2{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ state at subsequent gas collisions, and by the reduction of the remainder of them by several distinct processes to the $1{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ state. The effective cross sections for the different processes are given.