The infrared spectrum of NH3-dn trapped in solid neon

The infrared spectra of normal and deuterium-enriched Ne:NH₃=1600:1 deposits at 4.3 K have been observed, and the structure associated with almost all of the vibrational fundamentals has been assigned. Although the most prominent absorptions arise from the ground-state J=0 level(s), incomplete nuclear-spin equilibration enhances the contribution of absorptions arising from the ground-state J=1 levels. As had been proposed in an earlier study, the inversion splitting for the ν₂ fundamental is appreciably reduced from that observed for the gas-phase molecule, and the rotational structure associated with the J=1 levels of the vibrationally excited molecule is somewhat perturbed. Ammonia is trapped in two different types of site in solid neon. Matrix shifts from the corresponding gas-phase absorptions amount to only a few cm⁻¹, and are smaller than those previously reported for ammonia trapped in an argon matrix.