ExoMol line lists – LXVIII: Rotation-vibration-electronic spectroscopy of Potassium Hydride (KH)

Abstract Comprehensive line lists for three potassium hydride (KH) isotopologues, 39KH, 40KH and 41KH applicable at high temperatures are presented. Ab initio potential energy curves (PECs), non-adiabatic couplings (NACs), spin-orbit curves, electronic angular momentum curves, and (transitions) dipole moment curves (DMCs) are generated for the X 1Σ+, A 1Σ+, B 1Π, C 1Σ+, a 3Σ+, c 3Σ+ and b 3Π states of KH using the MRCI method. Empirical energy levels are determined for the X 1Σ+, A 1Σ+ and B 1Π states using the MARVEL (Measured Active Rotation Vibration Energy Levels) procedure, and used to refine the corresponding ab initio PECs of X 1Σ+, A 1Σ+ and B 1Π. These PECs and (T)DMCs are used to calculate energies, Einstein A coefficients, lifetimes and partition functions up to 10000 K covering wavenumbers below 40000 cm−1 (≥250 nm) and rotational excitations with J ≤ 130. Calculated energies and state lifetimes are generally in good agreement with experimental values. Emission to unbound X 1Σ+ states contributes significantly to lifetimes of A 1Σ+ rovibronic states. This study should facilitate detections of KH in exoplanet and stellar atmospheres. The Khan line lists are available from the ExoMol database at www.exomol.com.