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33. From clusters to condensed phase - FT IR studies of water

Author

Pogorelov, V., Doroshenko, I., Pitsevich, G., Balevicius, V., Sablinskas, V., Krivenko, B., Pettersson, Lars G. M., Pogorelov, V., Doroshenko, I., Pitsevich, G., Balevicius, V., Sablinskas, V., Krivenko, B., and Pettersson, Lars G. M.

Abstract

Intermolecular hydrogen bonding, which is formed between water molecules in the condensed state, causes a variety of unique properties of liquid water. In this paper the results of experimental FT IR studies of water trapped in an Ar matrix as well as condensed water at temperatures from 133 to 293 K are presented. It is shown that the temperature evolution of the FTIR-spectra of water trapped in low-temperature matrices can be considered as an experimental model of the structure transformation of water during the phase transition from gas phase to condensed confined water. The comparison of the vibrational spectra of water in matrix isolation with the corresponding spectra of condensed water gives information about the peculiarities of H-bonded structures of water.

Published
2017
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34. MP4 Study of the Anharmonic Coupling of the Shared Proton Stretching Vibration of the Protonated Water Dimer in Equilibrium and Transition States

Author

Pitsevich, G., Malevich, A., Kozlovskaya, E., Mahnach, E., Doroshenko, I., Pogorelov, V., Pettersson, Lars G. M., Sablinskas, V., Balevicius, V., Pitsevich, G., Malevich, A., Kozlovskaya, E., Mahnach, E., Doroshenko, I., Pogorelov, V., Pettersson, Lars G. M., Sablinskas, V., and Balevicius, V.

Abstract

The structure and harmonic and anharmonic IR spectra of the protonated water dimer (PWD) were calculated in C-1,C- C-2.., and C-s, symmetry at the MP4/acc-pVTZ level of theory. We found that structure and IR spectra are practically identical in C-2 and C-1 symmetry, demonstrating that an equilibrium C-1 configuration of the PWD is not realized. Anharmonic coupling of the shared proton stretching-vibration with all other modes in the PWD in C-2 and C-s symmetry was the focus of this investigation. For this purpose, 28 two-dimensional potential energy surfaces (2D PES) were built at the MP4/acc-pVTZ level of theory and the corresponding vibrational Schrodinger equations were solved using the DVR method. Differences in the coupling of the investigated mode with other modes in the C-2 and C-s configurations, along with some factors that determine the red-or blue-shift of the stretching vibration frequency, were analyzed. We obtained a rather reasonable value of the stretching frequency of the bridging proton (1058.4 cm(-1)) unperturbed by Fermi resonance. The Fermi resonance between the fundamental vibration v7 and the combined vibration v(2) + v(6) of the same symmetry was analyzed through anharmonic second order perturbation theory calculations, as well as by 3D PES constructed using Q(2), Q(6), and Q(7) as normal coordinates. A significant (up to 50%) transfer of intensity from the fundamental vibration to the combined one was found. We have estimated the frequency of the bridging proton stretching vibration in the C-s configuration of the PWD based on calculations of the intrinsic anharmonicity and anharmonic double modes interactions at the MP4/acc-pVTZ level of theory (1261 cm(-1)).

Published
2017
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49. Infrared and Raman Spectra, DFT-Calculations and Spectral Assignments of Germacyclohexane.

Author

Aleksa, V., Ozerenskis, D., Pucetaite, M., Cotter, C., Guirgis, G. A., and Sablinskas, V.

Subjects
INFRARED spectroscopy, RAMAN spectroscopy, CYCLOHEXANE, VAPOR-liquid equilibrium, SOLID-liquid interfaces, ABSORPTION spectra, DENSITY functional theory
Abstract

Raman spectra of germacyclohexane in liquid and solid states were recorded and depolarization data obtained. Infrared absorption spectra of the vapor and liquid have been studied. The wavenumbers of the vibrational modes were derived in the harmonic and anharmonic approximation in B3LYP/ccpVTZ calculations. According to the calculations, germacyclohexane exists in the stable chair conformation, whereas a possible twist form should have more than 15 kJ·mol-1 higher enthalpy of formation what makes this conformer experimentally not observable. The 27 A' and 21 A" fundamentals were assigned on the basis of the calculations and infrared and Raman band intensities, contours of gas phase infrared spectral bands and Raman depolarization measurements. An average discrepancy of ca. 0.77% was found between the observed and the calculated anharmonic wavenumbers for the 48 modes. Substitution of carbon atom with Ge atom in the cyclohexane ring is reasoning flattening of the ring. [ABSTRACT FROM AUTHOR]

Published
2015
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