Lattice Vibration Spectra. XX. Infrared and Raman Spectra of BaCl 2 •2H 2 O and BaCl 2 •2D 2 O

The infrared absorption and laser Raman spectra of BaCl₂·2H₂O powder and single crystals as well as BaCl₂·2D₂O, partially deuterated, and isotopically dilute samples have been analyzed in the range from 30 to 4000 cm⁻¹. A revised interpretation of the observed water bands is given. The influence of the bond angle of the H₂O molecules both on Raman intensity of the water modes and frequency shift of the bending fundamentals is discussed. The librational modes are assigned with regard to isotopic shifts and intensities of these modes in the ir and Raman spectra. The predicted splitting of librational fundamentals of HDO molecules, which are in an asymmetric force field, has been observed. The amount of intramolecular and intermolecular coupling of the H₂O vibrations is discussed.