The hyperfine excitation of OH radicals by He

Hyperfine-resolved collisions between OH radicals and He atoms are investigated usingquantum scattering calculations and the most recent ab initio potential energy surface,which explicitly takes into account the OH vibrational motion. Such collisions play animportant role in astrophysics, in particular in the modelling of OH masers. Thehyperfine-resolved collision cross sections are calculated for collision energies up to2500 cm^-1 fromthe nuclear spin free scattering S-matrices using a recoupling technique. Thecollisional hyperfine propensities observed are discussed. As expected, the results fromour work suggest that there is a propensity for collisions with ΔF = Δj.The new OH−He hyperfine crosssections are expected to significantly help in the modelling of OH masers from current andfuture astronomical observations. Graphical abstract: .