Photoionization cross sections of the ground and first excited states of the OH radical

Abstract

We present a comprehensive study of photoionization of OH radicals from the ground and first excited electronic states. Cross sections and asymmetry parameters for the valence orbitals are reported for photon energies from near the threshold to 60 eV. The calculations have been performed with the $R$-matrix method. Two different continuum basis types, namely, the Gaussian and $B$-spline bases, are used to assess the quality of the description of the continuum. The results show both types of continuum bases provide a similar quality description in the near threshold resonant region, but the latter can predict more reliable photoionization observables in higher-energy regions. Our calculations are compared with available experimental and theoretical results, and the discussions are provided.