Vibration–rotational Einstein coefficients for HF/DF and HCl/DCl

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Abstract
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 Δv=1, 2, and 3 transitions for v≤6 for HF and v≤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≤25 for each v level. The higher v levels of HF were investigated using a Padé extrapolation of the experimental dipole function and a recently published ab initio function. Our Δv=1 Einstein coefficients for HF agree closely with those from an earlier experimentally based dipole function and with the new ab initio results for v≤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 Δv=1 transitions, ADX/AHX, were not changed significantly. Also, the changes in the ratios of the Einstein coefficients, Av,v−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(v,J) is discussed.