Infrared spectrum and ab initio calculations of the HNH+–Ne open-shell ionic dimer

Abstract

The IR photodissociation spectrum of the HNH⁺–Ne open-shell ionic complex has been recorded in the vicinity of the N–H stretch fundamentals of HNH⁺ (ν₁ and ν₃). The rovibrational analysis of the spectrum is consistent with a quasilinear proton-bound HNH⁺–Ne geometry in the ³Σ⁻ electronic ground state and an intermolecular separation R_H–Ne∽1.93 Å in the ground vibrational state. Ab initio calculations at the UMP2/aug-cc-pVTZ^# level confirm that the diradical character and quasilinearity of HNH⁺ are only a little affected by the weak interaction with Ne. The dissociation energy of the complex is calculated as D_e = 530 cm⁻¹.