Vibrational excitation of N2 during optical pumping of Hg by 253.7 mμ resonance radiation

The observed decay time and the population density of the metastable 6 3P0 state of mercury in a N2:Hg gas mixture are markedly reduced with increased duration of an intense 253.7 mμ resonance radiation pulse. We show that this phenomenon is due to a vibrational excitation of the nitrogen in the spin–orbit relaxation decay of the 6 3P1 to the 3P0 state of Hg which is followed by the quenching of the 3P0 state. Such quenching takes place by diffusion and deactivation of 3P0 at the walls or by a three-body excimer formation in the gas. Observations are confirmed by a numerical solution of the rate equations for the different excited states in the system. The impact of these results on the performance of the optically pumped Hg laser is discussed.