Buffer-gas effect on the rotovibrational line intensity distribution: Analysis of possible mechanisms

The effect of perturbing gas density on the intensity distribution in rovibrational absorption bands

“…The way, the van der Waals complexes are treated in Refs. [2,3] is somewhat misleading, however. That is why we find this interpretation worth of revisiting.…”

“…Experimental data on the rovibrational line intensity damping effect relate to the perturbation in the spectra of diatomic hydrogen halides (HCl or HF) in collision with rare gas atoms (Ar or Xe) [1][2][3]. The measured variations of s m as a function of the line numbers are shown in Figs.…”

“…The study of collisionally broadened rovibrational absorption lines in HCl and HF perturbed by Ar or Xe revealed a significant decrease in intensity of the low-lying rovibrational lines with increasing buffer gas pressure [1][2][3]. Recent measurements [3] in the fundamental and the first overtone of HCl perturbed by Ar in the range of pressures from 10 to 50 atm clearly demonstrate the effect of intensity deficit for at least three low J rotational lines, both in the P and R branches.…”

“…[2,3] as a plausible cause of variation of absorption line intensities with respect to the buffer gas density. The authors of Ref.…”

“…A model describing the effect of the formation of weakly bound complexes on line intensities was first proposed in Ref. [2] and was then considered without modifications in Ref. [3].…”