Spectroscopic databases

Another important branch of our research activity is developing and populating spectroscopic databases that provide line-by-line reference molecular spectra. Our main direction in this field is providing collision-induced line-shape parameters based on accurate ab initio quantum-scattering calculations.

For the simplest molecular systems, such as He-perturbed molecular hydrogen, we have provided full datasets of collision-induced line-shape parameters covering rovibrational transitions in H₂ [53] and HD [51]. For more complex H₂-perturbed H₂ and HD systems, we have provided results for the first several lines [67] with the long-term goal of extending the data coverage.

Our current interests include line-shape calculations for molecular systems relevant to the Earth’s atmosphere, including CO [61], O₂ [45], HCl [64], HF and HCN [74] with N₂ and O₂ as perturbers.

We also work on introducing collisional line-shape models to spectroscopic databases that include beyond-Voigt effects such as speed dependence of collisional broadening and shifting and the complex Dicke effect. This activity includes the HITRAN parameterization of the Hartmann–Tran profile [19], analysis of temperature-dependence representations including the double power law [40], and the development of the modified Hartmann–Tran profile now recommended for beyond-Voigt applications in HITRAN [76].

In parallel, we are involved in calculations of line intensities for simple diatomic molecules [70, 72]. These projects are pursued in close collaboration with the HITRAN group.