Ultrafast temporal evolution of liquid water (IMAGE)
Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
Caption
a, Schematic diagram of the experimental system. A broadband THz pump pulse (peak electric field strength of 14.9 MV/cm, centre frequency of 3.9 THz, and bandwidth of 1-10 THz) excites liquid water to initiate transient birefringence caused by THz Kerr effect (TKE), which is monitored by an 800 nm probe pulse that becomes elliptically polarized as it passes through the water film. b, The TKE responses of liquid water and heavy water are demonstrated for comparison. The relatively large damping coefficient of heavy water in the stretching mode corresponds to the faster energy decay process of the harmonic oscillator, resulting in a reduction in the second peak of the TKE response compared to that of water. c, The TKE response is assigned to the superposition of four components, among which the bidirectional contributions of bending and stretching modes play dominant roles. The proposed a hydrogen bond oscillator model based on the Lorentz dynamic equation to describe the dynamics of the intermolecular modes of liquid water and successfully reproduced the measured TKE responses.
Credit
Hang Zhao, Yong Tan, Liangliang Zhang, Rui Zhang, Mostafa Shalaby, Cunlin Zhang, Yuejin Zhao, and Xi-Cheng Zhang
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