Linewidth variation in the spectrum of NaI

Although the predissociation linewidths for given potential curves have been calculated routinely for near-diabatic photoabsorption processes, there is not yet a well established method for computing linewidths in the near-adiabatic situation. In this paper, a formula derived from Fano's theory is applied to estimate the variation in linewidth in the u.v. spectrum of NaI, which is of the near-adiabatic nature. The results are verified by comparison with the spectra calculated from direct solutions of coupled Schrodinger's equations. It is also found that the results are in good agreement with the predictions from Child's semiclassical theory and with the experimental observations by Schaefer et al [S. H. Schaefer, D. Bender, and E. Tiermann, Chem. Phys. 89, 65 (1984); Ref. 1].