Rotation of water in solid parahydrogen and orthodeuterium

The far-infrared spectra of solid orthodeuterium and solid normal deuterium are presented and compared to the corresponding spectra of solid parahydrogen and solid normal hydrogen. Spectra of water in orthodeuterium are compared to spectra of water in parahydrogen. The water rotation constants in orthodeuterium are approximately 80% of the rotation constants of water in parahydrogen. The S(0)(0) band of orthodeuterium gets a strong satellite in the presence of water. The position and width of the satellite depends on the isotopic composition of the water present. If there is a corresponding satellite in parahydrogen it is weak and closer to the S(0)(0) band of the matrix. The conclusion of the paper is that interaction between guest rotation and the rotation of matrix molecules must be taken into account to explain the reduction of the rotation constants in orthodeuterium.