Anharmonicities and coherent vibrational dynamics of phosphate ions in bulk H2O

文献情報

出版日 2015-10-01

DOI 10.1039/C5CP04502A

インパクトファクター 3.676

著者

Rene Costard, Tobias Tyborski, Benjamin P. Fingerhut

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要旨

Phosphates feature prominently in the energetics of metabolism and are important solvation sites of DNA and phospholipids. Here we investigate the ion H2PO4− in aqueous solution combining 2D IR spectroscopy of phosphate stretching vibrations in the range from 900–1300 cm−1 with ab initio calculations and hybrid quantum-classical molecular dynamics based simulations of the non-linear signal. While the line shapes of diagonal peaks reveal ultrafast frequency fluctuations on a sub-100 fs timescale caused by the fluctuating hydration shell, an analysis of the diagonal and cross-peak frequency positions allows for extracting inter-mode couplings and anharmonicities of 5–10 cm−1. The excitation with spectrally broad pulses generates a coherent superposition of symmetric and asymmetric PO2− stretching modes resulting in the observation of a quantum beat in aqueous solution. We follow its time evolution through the time-dependent amplitude and the shape of the cross peaks. The results provide a complete characterization of the H2PO4− vibrational Hamiltonian including fluctuations induced by the native water environment.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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