New infrared spectra of CO2-Ne: fundamental for CO2-22Ne isotopologue, intermolecular bend, and symmetry breaking of the intramolecular CO2 bend

Abstract

The infrared spectrum of the weakly-bound CO2-Ne complex is studied in the region of the carbon dioxide nu3 fundamental vibration (~2350 cm-1), using a tunable OPO laser source to probe a pulsed supersonic slit jet expansion. For the fundamental CO2 transition (v1, v2l2, v3) = (0001) <-- (0000), both CO2-20Ne and CO2-22Ne are assigned and analyzed in combination with available microwave data to obtain the best currently available molecular parameters. In addition, combination bands involving the intermolecular bending mode are observed for both isotopologues, leading to the determination of the bending frequency in the CO2 excited state, which is 17.717 cm-1 for CO2-20Ne and 17.726 cm-1 for CO2-22Ne. For the hot band CO2 transition, (0111) <-- (0110), detection of the weak CO2-Ne spectrum reveals the symmetry breaking of the CO2 nu2 bending mode induced by the Ne atom, with the out-of-plane component determined to lie 0.057 cm-1 higher in energy than the in-plane component.