Fully quantum calculations of the line shape parameters for 1-0 P(22) and P(31) lines of CO perturbed by He or Ar

This work reports the full quantum calculations of the spectral line shape parameters for the P(22) line of (CO)-C-13 and the P(31) line of (CO)-C-12 in the fundamental band perturbed by He or Ar from 20 to 1000 K for the first time. The generalized spectroscopic cross sections of CO-He/Ar indicate that the Dicke narrowing effect competes with the pressure broadening effect. The pressure broadening can be explained by the dynamic behaviors of intermolecular collisions. The intermolecular inelastic collisions contribute more than 95% to the pressure broadening in both CO-He and CO-Ar systems at high temperatures. Regarding the state-to-state inelastic contributions to pressure broadening, the maximum contribution out of the final state of a given line is close to that out of the initial state. The Dicke narrowing effect influences the line shape profile significantly at high temperatures, which suggests that it is indispensable for reproducing the spectral line profile. With the Dicke narrowing effect, the calculated pressure-broadening coefficients and spectral intensity distribution are in good agreement with the available experimental observations. Published under an exclusive license by AIP Publishing.

Automated summary

This work presents the quantum calculations of the spectral line shape parameters for (CO)-C-13 and (CO)-C-12 in the fundamental band, perturbed by He or Ar from 20 to 1000 K. The results show that the Dicke narrowing effect competes with the pressure broadening effect, and intermolecular inelastic collisions contribute significantly to the pressure broadening. The presence of the Dicke narrowing effect is essential for reproducing the spectral line profile and is in agreement with experimental observations.