Photoassociation spectroscopy of collisional pairs of mercury atoms: Determination of parameters of molecular terms

The photoassociation spectrum of an equilibrium vapor of mercury atoms in the range of 34960–37250 cm^?1 is recorded with the help of a tunable laser in observations of laser-induced fluorescence. The Franck-Condon fstructure, i.e., periodic variations in absorption intensity against a continuous background, is observed. The structure makes it possible to determine spectroscopic parameters of the upper attractive potential and the lower repulsive potential including that with a van der Waals well. The absorption spectrum of collisional pairs of mercury atoms is calculated using the Numerov-Cooley procedure for integrating the Schrödinger equation. Potential curves of the upper and lower states Hg₂(D1_u) and Hg₂(X0 _g ⁺ ) are determined by comparing the calculated spectra with the experimental one.