VIOLET EMISSION FROM OPTICALLY-EXCITED MERCURY-VAPOR - KINETICS OF THE FORMATION AND DECAY OF EXCITED DIMERS AND TRIMERS

A new electronic systems has been observed from excited Hg vapour, which is assigned to collisionally induced emission from the Hg2 O±g first excited states of the dimer: Hg2O±g + M → 2Hg(6 1S0) + M + hv(γmax 3950 A). For M = N2, the rate coefficient is 5.3(±0.7) × 10-19 cm3 molecule-1 at 298 K. From time resolved measurements of the luminescence in the afterglow following pulsed excitation, the decay rate of the green emission, in an excess of N2, is shown to be a linear function of [Hg][N2]. It is concluded that the reaction which controls the decay of the excitation is formation of an excited trimer in a termolecular reaction; the trimer is the carrier of the green emission: Hg2 O±g + Hg(6 1S0 + Hg(61S0 + N2 → Hg3 3Πu + N2. The rate coefficient is 1.10(±0.07) × 10-30 cm6 molecule-2 s-1 at 298 K. © 1979.