Mid/near infrared spectroscopy of the H2Cl+Ar cation complex compared to the predictions of anharmonic theory

Highlights: • H₂³⁵Cl⁺ Ar ions are produced via pulsed discharge in a supersonic expansion. • The photodissociation spectrum of H₂³⁵Cl⁺ Ar is studied at from 1000 to 7350 cm⁻¹. • Spectra are predicted with Second Order Vibrational Perturbation Theory (VPT2). • Rotational structure of several bands give insight into excited state structures. The H₂³⁵Cl⁺Ar cation complex was prepared by electrical discharge in a supersonic expansion of argon doped with HCl and hydrogen. The ion was mass selected in a reflectron time-of-flight spectrometer and investigated with infrared photodissociation spectroscopy in the regions of 1000–4550 and 4850–7350 cm⁻¹. Anharmonic vibrational frequencies were computed with VPT2 at the CCSD(T)/cc-pVTZ level of theory. The previously unreported ν₃ fundamental at 2211 cm⁻¹ and several new combinations and overtones are reported. VPT2 theory at this level confirms the H-bound structure of the complex and provides an accurate description of the anharmonic vibrations in this system.