二维太赫兹-太赫兹拉曼光谱中的和频信号。

Sum-Frequency Signals in 2D-Terahertz-Terahertz-Raman Spectroscopy.

机构信息

Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.

Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States.

出版信息

J Phys Chem B. 2020 Oct 8;124(40):8904-8908. doi: 10.1021/acs.jpcb.0c07935. Epub 2020 Sep 28.

DOI:10.1021/acs.jpcb.0c07935

PMID:32897705

Abstract

We demonstrate that halogenated methane (HM) two-dimensional (2D)-terahertz-terahertz-Raman (2D-TTR) spectra are determined by the complicated structure of the instrument response function (IRF) along ω and by the molecular coherences along ω. Experimental improvements have helped increase the resolution and dynamic range of the measurements, including accurate THz pulse shape characterization. Sum-frequency excitations convolved with the IRF are found to quantitatively reproduce the 2D-TTR signal. A new reduced density matrix model that incorporates sum-frequency pathways, with linear and harmonic operators, fully supports this (re)interpretation of the 2D-TTR spectra.

摘要

我们证明，卤代甲烷（HM）二维（2D）太赫兹-太赫兹拉曼（2D-TTR）光谱由仪器响应函数（IRF）沿 ω 的复杂结构和分子相干性沿 ω 决定。实验改进有助于提高测量的分辨率和动态范围，包括准确的太赫兹脉冲形状特征。与 IRF 卷积的和频激发被发现可以定量再现 2D-TTR 信号。一个新的简化密度矩阵模型，包含和频途径、线性和谐波算子，完全支持对 2D-TTR 光谱的这种（重新）解释。