二维拉曼太赫兹光谱学中的水：理论。

Two-dimensional-Raman-terahertz spectroscopy of water: theory.

机构信息

Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.

出版信息

J Chem Phys. 2012 Mar 7;136(9):094516. doi: 10.1063/1.3691601.

Abstract

We discuss the hybrid 2D-Raman-THz spectroscopy of liquid water. This two-dimensional spectroscopy is designed to directly work in the low-frequency range of the intermolecular degrees of freedom. The information content of 2D-Raman-THz spectroscopy is similar to 2D-Raman or 2D-THz spectroscopy, but its experimental implementation should be easier. That is, 2D-Raman-THz spectroscopy is a 3rd-order nonlinear spectroscopy and as such completely avoids cascading of consecutive 3rd-order signals, which turned out to be a major difficulty in 5th-order 2D-Raman spectroscopy. On the other hand, it does not require any intense THz pump-pulse, the lack of which limits 2D-THz spectroscopy to the study of semiconductor quantum wells as the currently available pulse energies are too low for molecular systems. In close analogy to 2D-Raman spectroscopy, the 2D-Raman-THz response of liquid water is simulated from an all-atom molecular dynamics simulation, and the expected spectral features are discussed.

摘要

我们讨论了液态水的混合 2D-Raman-THz 光谱学。这种二维光谱学旨在直接在分子间自由度的低频范围内工作。2D-Raman-THz 光谱学的信息含量与 2D-Raman 或 2D-THz 光谱学相似，但其实验实现应该更容易。也就是说，2D-Raman-THz 光谱学是一种三阶非线性光谱学，因此完全避免了连续三阶信号的级联，这在五阶 2D-Raman 光谱学中是一个主要的困难。另一方面，它不需要任何强的太赫兹泵浦脉冲，而太赫兹泵浦脉冲的缺乏限制了 2D-THz 光谱学对半导体量子阱的研究，因为目前可用的脉冲能量对于分子系统来说太低了。与 2D-Raman 光谱学非常相似，从全原子分子动力学模拟中模拟了液态水的 2D-Raman-THz 响应，并讨论了预期的光谱特征。