Spectroscopy and kinetics of the optically excited mercury–thallium excimer

Pulsed laser excitation at 380 nm is used to study the kinetics of the B 2Σ1/2 state of HgTl. Results are obtained qualitatively by time-resolved spectroscopy of the bands around 459 and 656 nm and quantitatively for the following processes by decay time measurements: (i) three-body association, Tl*+2Hg→HgTl*+Hg, k3 = 1×10−31 cm6 s−1; (ii) spontaneous decay of 7 2S1/2 state of Tl, τ0 = 7.4 ns; (iii) decay of high-lying vibrational levels of the B state: spontaneous decay, τ0 = 9.1 ns, collisional relaxation and dissociation, k = 2.9×10−10 cm3 s−1; (iv) decay of low-lying vibrational levels of the B state: spontaneous decay, τ0 = 38.7 ns, collisional deactivation cross section σ≊2 Å2; (v) energy transfer from metastable Hg*, Hg*2 to Tl*, HgTl*, cross section σ = 165 Å2. Cw laser excitation is used to study the spectroscopy by analysis of the temperature dependence of the band shapes. The following dissociation energies are determined: B 2Σ1/2: 4400 cm−1, X 3/2: 2750 cm−1 and X 1/2: 800 cm−1. A gain measurement is performed, pumping the B state with a pulsed laser at 380 nm with 10 mJ pulse energy and probing in the fluorescence bands using a dye laser. Absorption is measured for all wavelengths of the bands.