Dissociation curves for nine low lying states of Tl2 from REP CI calculations

Dissociation curves for nine low lying states of Tl2 have been computed using relativistic effective potential and configuration interaction techniques. We can identify the molecular ground state as 0−u with a dissociation energy of 0.16 eV. 0+g and 1u states are about 0.1 eV higher in energy. The computed vibrational frequencies for these states are well below values from the Tl2 thermal emission spectrum. The discrepancy between our bond energy and the value (0.63 eV) given in recent mass spectrometric work is due, in part, to the use of inappropriate molecular parameters in the mass spectrometric analysis.