Ro-vibrational spectrum of H2O-Ne in the ν2 H2O bending region: A combined ab initio and experimental investigation

Abstract High resolution ro-vibrational transitions of the H 2 O-Ne complex in the ν 2 bending region of H 2 O at 6 μm have been measured using a rapid scan infrared spectrometer based on an external cavity quantum cascade laser and an astigmatic multipass optical cell. To aid the spectral assignment, a four-dimension potential energy surface of H 2 O-Ne which depends on the intramolecular bending coordinate of the H 2 O monomer and the three intermolecular vibrational coordinates has been constructed and the rovibrational transitions have been calculated. Three ortho and two para H 2 O- 20 Ne bands have been identified from the experimental spectra. Some weaker transitions belonging to H 2 O- 22 Ne have also been identified experimentally. Spectroscopic fits have been performed for both the experimental and theoretical transition frequencies using a simple pseudo-diatomic Hamiltonian including both Coriolis coupling and Fermi resonance terms. The experimental and theoretical spectroscopic constants thus obtained have been compared. Further improvements needed in the potential energy surface and the related spectral simulation have been discussed.