Laser spectroscopy of the HgCd exciplex.

Abstract

Fluorescence and excitation spectra of HgCd were studied using pump-and-probe methods of laser spectroscopy with time resolution. A Hg-Cd vapor mixture, contained in a sealed quartz cell at 700 K, was irradiated by consecutive pump and probe dye-laser pulses. The pump radiation produced a population of Cd 5 $^{3}$${\mathit{P}}_{1}$ atoms whose three-body collisions with Hg atoms resulted in the formation of HgCd excimers in the A${0}^{\mathrm{\ensuremath{-}}}$, A${0}^{+}$, and A1 states, correlated with the Cd 5 $^{3}$P+Hg 6 $^{1}$S manifold, which decayed, emitting a previously reported 4600-\AA{} fluorescence continuum. The probe pulses, delayed by 450 ns, excited the excimers to the higher-lying C${0}^{+}$ (Cd 5 $^{1}$${\mathit{P}}_{1}$+Hg 6 $^{1}$${\mathit{S}}_{0}$) state, which decayed to the repulsive X${0}^{+}$ ground state, emitting fluorescence in the 2400--2650-\AA{} region. We also observed a bound-bound excitation spectrum in the 5800--7100-\AA{} region. A study of the time evolution of the excimer fluorescence yielded an approximate value for the three-body rate coefficient for HgCd formation, and an analysis of the spectra produced spectroscopic constants for the states involved in the transitions.