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Femtosecond 2DIR spectroscopy of the nitrile stretching vibration of thiocyanate anions in liquid-to-supercritical heavy water. Spectral diffusion and libration-induced hydrogen-bond dynamics.
- Source :
- Physical Chemistry Chemical Physics (PCCP); 11/28/2015, Vol. 17 Issue 44, p29776-29785, 10p
- Publication Year :
- 2015
-
Abstract
- Femtosecond two-dimensional infrared (2DIR) spectroscopy was carried out to study the dynamics of vibrational spectral diffusion of the nitrile stretching vibration of thiocyanate anions (S–C≡N<superscript>−</superscript>) dissolved in liquid-to-supercritical heavy water (D<subscript>2</subscript>O). The 2DIR line shapes were used to extract through a nodal slope analysis quantitative information about the correlation function for temporal fluctuations of the CN-stretching frequency. The inverse nodal slope could be fitted phenomenologically by a simple double-exponential decay whose predominant component had a time constant ranging between 300 fs and 1 ps depending on the temperature. The temperature dependence is interpreted in terms of solvent structural fluctuations that are driven by the librational motions of the D<subscript>2</subscript>O molecules located in the first solvation shell of the anion. Complementary molecular dynamics simulations of the SCN<superscript>−</superscript>/D<subscript>2</subscript>O system indicate that the breaking and making of hydrogen-bonds between the terminal N-atom of the anion and the D<subscript>2</subscript>O molecules are induced by the same solvent-shell librational degrees of freedom that drive the vibrational line broadening dynamics seen in the 2DIR experiment. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14639076
- Volume :
- 17
- Issue :
- 44
- Database :
- Complementary Index
- Journal :
- Physical Chemistry Chemical Physics (PCCP)
- Publication Type :
- Academic Journal
- Accession number :
- 110768373
- Full Text :
- https://doi.org/10.1039/c5cp05237h