Ultrafast vibrational dynamics of water at a charged interface revealed by two-dimensional heterodyne-detected vibrational sum frequency generation.
Ultrafast vibrational dynamics of water at a charged interface revealed by two-dimensional heterodyne-detected vibrational sum frequency generation.
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DOI：
10.1063/1.4747828
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发表时间：
2012-09
期刊：
影响因子：
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通讯作者：
P. Singh;S. Nihonyanagi;S. Yamaguchi;T. Tahara
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文献类型：
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作者：
P. Singh;S. Nihonyanagi;S. Yamaguchi;T. Tahara
二维外差探测振动和频产生（2D HD-VSFG）光谱首次进行了水界面。从带正电荷的表面活性剂/水与同位素稀释水（HOD/D（2）O）的界面获得了OH伸缩区的2D HD-VSFG光谱，以揭示水在带电界面处的飞秒振动动力学。2D HD-VSFG光谱在光激发后立即对角延长，清楚地表明界面水中的不均匀性。由于光谱扩散，这种伸长在300 fs处几乎消失。有趣的是，在0 fs处的2D HD-VSFG光谱显示出与本体水中的相应2D IR光谱相反的不对称形状：当泵浦波数变得更高时，漂白信号的带宽变得更窄。这表明，在带电界面处的氢键重排的动力学和机制是显着不同的散装水。
Two-dimensional heterodyne-detected vibrational sum frequency generation (2D HD-VSFG) spectroscopy is performed for an aqueous interface for the first time. The 2D HD-VSFG spectra in the OH stretch region are obtained from a positively charged surfactant/water interface with isotopically diluted water (HOD/D(2)O) to reveal the femtosecond vibrational dynamics of water at the charged interface. The 2D HD-VSFG spectrum is diagonally elongated immediately after photoexcitation, clearly demonstrating inhomogeneity in the interfacial water. This elongation almost disappears at 300 fs owing to the spectral diffusion. Interestingly, the 2D HD-VSFG spectrum at the 0 fs shows an oppositely asymmetric shape to the corresponding 2D IR spectrum in bulk water: The bandwidth of the bleach signal gets narrower when the pump wavenumber becomes higher. This suggests that the dynamics and mechanism of the hydrogen bond rearrangement at the charged interface are significantly different from those in bulk water.