在2D材料中建立层特性欧洲杯足球竞彩

The properties of few-layered materials are significantly different when compared to their bulk phase. Their tunable optoelectronic characteristics are largely governed by the interactions between the vertically stacked layers, and are affected by the number and orientation of the layers.

对应于这些层间相互作用的振动，称为剪切模式，表现为低频拉曼峰非常接近激光雷利线，而传统拉曼光谱未检测到。但是，使用低频/THZ-Raman^®促进了过渡金属二甲化物（TMD）材料的剪切模式的测量，从而使方向和层数明确而清晰地测量。欧洲杯足球竞彩

Figure 1.TMD的广义化学结构，显示了金属（灰色）和硫代基因（黄色）原子，改编自S. Mouri，K。Matsuda等，Nano Lett。13，（2013）5944。₂substrates. Red dot indicates the approximate location of the Raman measurement (Bottom).†

†The MoSe₂sample was synthesized and characterized at the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory (X. Li, A.A. Puretzky; see ACS Nano 9, 6333-6342 (2015) for details).

The THz-Raman^®解决方案

出现THZ-RAMAN®系统has extended the range of conventional Raman spectroscopy to the THz/low frequency Raman regime, where lattice modes correlating to the material structure are found and inter-layer modes can be clearly and quickly observed. While the traditional Raman spectra might hint at similar information, they are usually indirect and not easily verified using ab-initio simulations.

This article discusses the study of a sample of MoSe₂两层的两个不同相对方向的分布（图1）。连贯的TR-Micro-532 THZ-Raman^®system coupled to a single-stage spectrometer with a spectral resolution of 1.5 cm^-1使用在532 nm处的激发来收集拉曼光谱数据。图2显示了归一化的THZ-Raman^®spectra of the two orientations of MoSe₂。

Figure 2.标准化的Thz-Raman^®两层Mose的光谱₂欧洲杯足球竞彩材料显示了相应的峰值变化和峰值变化，峰值对应于242 cm的散装模式^-1（顶部）和剪切模式在18厘米处^-1(Bottom)

THz-Raman^®Analysis

The Raman spectra shown in Figure 2 demonstrate that irrespective of orientation, both the two-layer MoSe₂欧洲杯足球竞彩材料显示出平面外散装模式为242厘米处的峰值^-1in the Raman spectrum. The single layer MoSe₂不显示18厘米处的剪切模式^-1。

On the other hand, for the two-layer MoSe₂案例，剪切模式峰值在18.9厘米处^-1, as determined by a center of mass analysis. When the MoSe₂层的定向是同心，峰强度的大幅变化，呈茎颜色转移至18.4厘米^-1观察到。这表明有关2D材料中有关层的方向和数量的直接信息可以由THZ-Raman提供欧洲杯足球竞彩^®spectroscopy.

Atomic force and scanning tunneling microscopies can be employed to establish the exact atomic registration between different layers. However, they are slow techniques and demand expensive instrumentation and off-line analysis. THz-Raman^®offers a fast, cost-effective and non-destructive solution for fast prototyping of two dimensional materials.

特征

• 同时化学和结构分析
• Sensitivity to defects and dopants in the 2D material structure
• 方向与峰位置和幅度的直接相关
• 定量分析层
• Direct measurement of inter-layer vibrations in few-layered materials
• Directly calculate THz-Raman^®spectra using ab-initio calculations

结论

连贯的专利THZ-Raman^®光谱系统已将常规拉曼光谱学的范围扩展到THZ/低频制度。结果，可以同时分析化学成分和分子结构的复杂材料表征。欧洲杯足球竞彩全部THZ-RAMAN®系统具有强大的，紧凑和插件的平台，可提供非凡的速度，吞吐量和易用性，所有这些平台都以可承受的价格。具有广泛的样品接口，从488 nm到1064 nm的广泛的激发波长和可选的极化控制^®可以成功用于任何应用程序的解决方案。

This information has been sourced, reviewed and adapted from materials provided by Coherent.

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