Hyperfine excitation of linear molecules by para- and ortho-H2: application to the HCl-H2 system.

The determination of hyperfine structure resolved excitation cross sections and rate coefficients due to H2 collisions is required to interpret astronomical spectra. In this paper, we present several theoretical approaches to compute these data. An almost exact recoupling approach and approximate sudden methods are presented. We apply these different… (More)