Calculated OH-stretching vibrational transitions in the water-nitrogen and water-oxygen complexes

We have calculated the fundamental and overtone OH-stretching vibrational band intensities of the water-nitrogen (H2O.N-2) and water-oxygen (H2O.O-2) complexes. The calculations use the harmonically coupled anharmonic oscillator local mode model with local mode parameters obtained from scaled ab initio calculations and ab initio calculated dipole moment functions. The H2O.N-2 and H2O.O-2 complexes are weakly bound and the individual molecular units are only slightly perturbed by complexation, unlike what is found for the water dimer (H2O.H2O) and the water-nitric acid complex (H2O.HNO3). The fundamental OH-stretching intensity in H2O.N-2 is enhanced and the first overtone intensity weakened compared to H2O as an effect of the hydrogen bonding. In H2O.O-2 the OH-stretching intensities are comparable to those of H2O. On a per water unit basis, the calculated OH-stretching intensities of the higher overtones of H2O.N-2 and H2O.O-2 are similar to those of H2O.H2O. The possible effect of H2O.N-2 and H2O.O-2 on the atmospheric absorption of solar radiation is discussed.