Electronic spectroscopy and excited state mixing of OThF

Abstract

Electronic spectra for OThF have been recorded using fluorescence excitation and two-photon resonantly enhanced ionization techniques. Multiple vibronic bands were observed in the 340–460 nm range. Dispersed fluorescence spectra provided ground state vibrational constants and evidence of extensive vibronic state mixing at higher excitation energies. Two-photon ionization measurements established the ionization energy for OThF of 6.283(5) eV. To guide the assignment of the OThF spectra, electronic structure calculations were carried out using relativistic equation-of-motion coupled-cluster singles and doubles methods. These calculations indicated that spin–orbit induced mixing of the 32A″ and 42A′ states was mediated by a seam of potential energy surface intersections.