Rovibrational collisional cross sections and rate coefficients for the OH + He system

Many ongoing investigations in support of Cosmic Origins science goals to study the formation of stars, birth of planetary systems, and delivery of volatiles to Earth, rely on observations of OH emission. The Hydroxyl radical (OH) has been widely observed in the young stellar objects and many other astrophysical environments. Further, its collisional rate coefficients with the dominant colliders are of astrophysical importance in modeling molecular emission in non-local thermodynamic equilibrium (NLTE) environments. In this work, we present fine-structure-resolved rovibrationally inelastic excitation cross sections of OH with atomic Helium using both the close-coupling method and the coupled-states approximation. As far as we are aware, this is the first calculation of fine-structure-resolved vibrational transitions for this complicated open-shell molecule.This work was partially supported by NASA Grant 80NSSC21K1464.