Chen Ligang, Ren Guanhua, Liu Liyuan, Zhou Lu, Li Shaoxian, Zhu Zhongjie, Zhang Jianbing, Zhang Wentao, Li Yanfeng, Zhang Weili, Zhao Hongwei, Han Jiaguang
Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; Shanghai Advanced Research Institute Zhangjiang Lab, Chinese Academy of Sciences, Shanghai 201210, China; Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Jun 5;254:119671. doi: 10.1016/j.saa.2021.119671. Epub 2021 Mar 8.
Terahertz spectral features of alkali halide crystals were studied with the combination of broadband terahertz time-domain spectroscopy and the solid-state-based density functional theory calculations. To understand the particular modes of the observed terahertz features of the alkali halide crystals, the resonant modes of KCl and CsCl were analyzed using face-centered cubic and body-centered cubic lattice models, respectively. The results show that the characteristic terahertz absorption peaks could be assigned to the lattice vibration of the ionic crystals. Furthermore, the terahertz responses of a series of alkali halides were recorded, and obvious absorption peaks were observed in each salt in the frequency region below 8.5 THz. What is more interestingly is that the frequencies of these observed peaks are red-shifted with the increases of the mass and radius of the ions. This correlation between the resonant frequency of the lattice vibration, the reduced atomic mass, and the equilibrium distance between the ions agrees well with the harmonic oscillator model.
结合宽带太赫兹时域光谱和基于固态的密度泛函理论计算，研究了碱金属卤化物晶体的太赫兹光谱特征。为了理解碱金属卤化物晶体观测到的太赫兹特征的特定模式，分别使用面心立方晶格模型和体心立方晶格模型分析了KCl和CsCl的共振模式。结果表明，特征太赫兹吸收峰可归因于离子晶体的晶格振动。此外，记录了一系列碱金属卤化物的太赫兹响应，并且在每种盐中低于8.5太赫兹的频率区域观察到明显的吸收峰。更有趣的是，这些观测到的峰的频率随着离子质量和半径的增加而发生红移。晶格振动的共振频率、折合原子质量和离子间平衡距离之间的这种相关性与谐振子模型非常吻合。
