Infrared Spectroscopic Evidence for the Rotation of the Water Molecule in Solid Argon

Abstract

High‐resolution spectra of H₂O, HDO, and D₂O suspended in solid Ar have been observed in the range 4°—27°K. Evidence has been obtained for the rotation of these species in Ar matrices. The majority of the observed lines are found to be in very good agreement with low‐J transitions of the gas spectra, allowing for a small matrix shift. Transitions arising from both spin modifications of H₂O and D₂O have been observed and the observed intensities suggest that a large degree of spin equilibration has taken place. A small contamination of O₂ may be responsible for this. A perturbation of one of the rotational levels of ν₂—H₂O is discussed.