Raman spectroscopic and theoretical study of liquid and solid water within the spectral region 1600–2300cm−1

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 196; pp. 406 - 412
• Main Authors: Kozlovskaya, E.N., Pitsevich, G.A., Malevich, A.E., Doroshenko, O.P., Pogorelov, V.E., Doroshenko, I.Yu, Balevicius, V., Sablinskas, V., Kamnev, A.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.05.2018
• Subjects: Discrete variable representation (DVR); Intensities of Raman lines; PES; Raman spectra; Water; Water; Raman spectra; Intensities of Raman lines; Discrete variable representation (DVR); PES
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2018.01.071

Raman spectra of liquid water and ice were measured at different temperatures. The intensity of the band assigned to bending vibrations of water molecules was observed to decrease at the liquid-to-solid transition, while the Raman line near 2200cm−1 showed an anomalously high intensity in the solid phase. A tetrahedral model was used for computer analysis of the observed spectral changes. Quantum-chemical calculations of the structure, normal vibrations and Raman spectra in the harmonic approximation, as well as frequencies and intensities of some vibrations using 1D and 2D potential energy surfaces, were carried out using B3LYP with the cc-pVTZ basis set. The influence of the number of hydrogen bonds on the frequency and Raman activity of the bending vibrations was analyzed. The possibility of hydrogen bond weakening upon excitation of the combined bending-rocking vibration due to the large amplitude of this vibration is considered. The mystery of the unusually high relative Raman intensity of the water line near 2200cm−1 was in the focus of this investigation. To find the Raman intensity of the librational and bending combined vibration of water, 2D PES and 2D surfaces of the polar tensor components were calculated using natural rocking and bending coordinates. The possible impact of the large-amplitude motion in this vibration on the intensity of the 2200cm−1 line was analyzed. [Display omitted] •Raman spectra of water at 3°С and at −4°С were measured.•An unusually high relative Raman intensity of the line near 2200cm−1 was noted.•1–2D PES for the bending and librational water molecule motions were built.•Bending-rocking vibrations of water molecules in a Td environment were analyzed.