VIBRATION-ROTATIONAL EINSTEIN COEFFICIENTS FOR HF DF AND HCI DCI

The experimentally based dipole-moment functions have been combined with the best Rydberg-Klein-Rees potentials to calculate the vibration-rotational Einstein coefficients for HF, DF, HCl, and DCl. Calculations were done for the DELTA-upsilon = 1, 2, and 3 transitions for upsilon less-than-or-equal-to 6 for HF and upsilon less-than-or-equal-to 7 for HCl, which are in the range of the internuclear distance, r, for which the dipole moment functions are valid. The calculations were done for J less-than-or-equal-to 25 for each upsilon level. The higher upsilon levels of HF were investigated using a Pade extrapolation of the experimental dipole function and a recently published ab initio function. Our DELTA-upsilon = 1 Einstein coefficients for HF agree closely with those from an earlier experimentally based dipole function and with the new ab initio results for upsilon less-than-or-equal-to 6. Our results for HCl, however, represent a significant improvement over the Einstein coefficients currently in the literature. The isotopic ratio of Einstein coefficients for the DELTA-upsilon = 1 transitions, A(DX)/A(HX), were not changed significantly. Also, the changes in the ratios of the Einstein coefficients, A(upsilon, upsilon - 1)/A1.0, were less significant than the changes in the absolute magnitudes. The effect of high rotational energy on the Einstein coefficients for HF (upsilon,J) is discussed.