Interpretation of IR and Raman Line Shapes for H2O and D2O Ice Ih

• Published in: The journal of physical chemistry. B Vol. 116; no. 47; pp. 13821 - 13830
• Main Authors: Shi, L, Gruenbaum, S. M, Skinner, J. L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 29.11.2012
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp3059239

Noticeable differences between the vibrational (IR and Raman) spectra of neat H2O and D2O ice Ih are observed experimentally. Here, we employ our theoretical mixed quantum/classical approach to investigate these differences. We find reasonable agreement between calculated and experimental line shapes at both high and low temperatures. From understanding the structure of ice Ih and its vibrational exciton Hamiltonian, we provide assignments of the IR and Raman spectral features for both H2O and D2O ice Ih. We find that in H2O ice these features are due to strong and weak intermolecular coupling, not to intramolecular coupling. The differences between H2O and D2O ice spectra are attributed to the significantly stronger intramolecular coupling in D2O ice. Our conclusion for both H2O and D2O ice is that the molecular symmetric and antisymmetric normal modes do not form a useful basis for understanding OH or OD stretch spectroscopy.