The infrared spectrum of the N2H+–He ion-neutral complex

Abstract

Rotationally resolved, vibrational predissociation spectra of the HN⁺₂–He complex have been recorded in the region of the N–H stretch (3100–3200 cm⁻¹). The complex appears to be linear. Fitting of the measured lines to the pseudodiatomic expression ν=ν₀+(B^’_ν+B^‘_ν)m +(B^’_ν−B^‘_ν–D^’_ν+D^’_ν) m²−2(D^’_ν+D^‘_ν)m³ −(D^’_ν−D^‘_ν)m⁴ yields the following constants: ν₀=3158.419±0.009 cm⁻¹, B‘=0.3517±0.0005 cm⁻¹, D‘=(5.8±0.5)×10⁶ cm⁻¹, B’=0.3579 ±0.0005 cm⁻¹, D’=(3.9±0.6)×10⁶ cm⁻¹. The data support a proton bound He–HNN⁺ structure, with a 1.72 Å vibrationally averaged intermolecular bondlength, and an approximate intermolecular stretching frequency of 150 cm⁻¹.