Solvation Dynamics at the Air/Water Interface with Time-Resolved Sum-Frequency Generation
Solvation Dynamics at the Air/Water Interface with Time-Resolved Sum-Frequency Generation
复制标题
具有时间分辨和频生成的空气/水界面溶剂化动力学
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
K. Eisenthal
中科院分区：
文献类型：
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作者：
Y. Rao;N. Turro;K. Eisenthal
空气/水界面分子溶剂化的动力学已经通过飞秒时间分辨泵浦和频率发生（TR-SFG）进行了监测，该技术已被证明在超快旋转运动的研究中是可行的。在此报告的工作中，通过界面香豆素 314 (C314) 分子的飞秒光激发来监测溶剂化过程。在这些实验中，通过使用泵-TR-SFG 探针将 IR 脉冲调谐到羰基频率，使 SFG 信号与 C314 的羰基对称拉伸产生振动共振。获得两个溶剂化时间常数：230 ± 40 fs 和 2.17 ± 0.3 ps。这些结果在实验误差范围内与时间分辨二次谐波发生 (TR-SHG) 实验中测量的结果相同。这表明溶剂响应是由于溶剂化引起的 SFG 超极化中电子态能量的变化，而不是溶剂化对羰基振动数能量的影响。
The dynamics of molecular solvation at the air/water interface has been monitored with femtosecond time-resolved pump-sum frequency generation (TR-SFG), a technique that has been shown to be feasible in the study of ultrafast rotional motions. In the work reported here, the solvation process was monitored by femtosecond photoexcitation of interfacial coumarin 314 (C314) molecules. In these experiments, the SFG signal is brought into a vibrational resonance with the carbonyl symmetric stretch of C314 by tuning the IR pulse to the carbonyl frequency by using a pump-TR-SFG probe. Two solvation time constants were obtained, 230 ± 40 fs and 2.17 ± 0.3 ps. These results are the same within experimental error as those measured in time-resolved second-harmonic generation (TR-SHG) experiments. This suggests that the solvent response is due to solvation-induced shifts of the electronic-state energies in the SFG hyperpolarizability and not significantly to solvation effects on the energy of the carbonyl vibration no...