Computing photodissociation cross sections and quasi-continuum properties of the NH radical

Abstract

Photodissociation cross sections of NH for 250 > λ > 100 nm are studied using (i) the recently reported spectroscopic model of the five lowest electronic states of NH, (ii) a new set of ab initio potential energy, (transition) dipole moment, spin–orbit, and electronic angular momentum curves covering the region up to 100 000 cm−1, and (iii) the recently suggested approach for time-independent calculations of continuum spectra of molecules (Pezzella et al., 2022). Quasi-dissociative properties, including predissociation lifetimes and linewidths, of the c1Π state are studied using four state-of-the-art predissociative methods: stabilization, Airy-boundary conditions within the WKB approximation, phase–amplitude, and complex-scaling approaches. The methodologies developed and tested in this work will be used to produce photoabsorption and photodissociation spectra of NH and other diatomic species as part of the ExoMol database (Q.-H. Ni et al., 2025) at www.exomol.com.