The influence of nonequilibrium vibrational-rotational excitation of molecular hydrogen on the final concentration of HF molecules formed by the reaction F + H2 → HF + H in the photodissociation region at the boundary of the molecular cloud was studied by astrochemical modeling methods. The rate constant for the vibrational level v = 1 was obtained using a solution of the quantum scattering problem implemented in the ABC program. In a wide range of conditions within the framework of the model used, the effect of the hydrogen levels occupied under nonequilibrium conditions on the final HF/H2 ratio (which increases up to 10 times) is comparable in magnitude to the effect introduced by the uncertainty of the equilibrium constants used (the ratio changes ~2. 5 times).
Pakhan’yan et al. (Wed,) studied this question.