Resonant photodissociation of CoAr+ and CoKr+: Analysis of vibrational structure

Abstract

The transition‐metal rare‐gas diatomic ions, CoAr⁺ and CoKr⁺, generated and cooled in a supersonic expansion, are studied by visible resonant photodissociation for the first time. Photofragmentation excitation spectra exhibit sharp vibronic features which are members of several excited electronic state vibrational progressions in each molecular ion. Analysis of over 200 vibronic transitions in these spectra reveals details of the potential‐energy surfaces characterizing the bonding in these excited states. The adiabatic ground‐state dissociation energies of CoAr⁺ and CoKr⁺, determined as 4100 cm⁻¹ and 5400 cm⁻¹, respectively, are ca. 37% larger than the diabatic dissociation energy of an excited state which dissociates into 3d^{8 3}P₂ Co⁺¹S Ar(Kr) excited atoms and 95% larger than a state dissociating into 3d⁷4s ³F₂Co⁺¹S Ar(Kr) atoms. Vibrational frequencies, anharmonicities, electronic origins, and dissociation limits of three electronic states in each molecule have been determined. A simple electrostatic binding model for these transition‐metal rare‐gas species is discussed.