Raman spectroscopy provides rich optical signals that can be used, after data analysis, to assess if a graphene layer is pristine, doped, damaged, functionalized, or stressed. The area being probed by a conventional Raman spectrometer is, however, limited to the size of the laser beam (∼1 µm); hence, detailed mapping of inhomogeneities in a graphene sample requires slow and sequential acquisition of a Raman spectrum at each pixel. Studies of physical and chemical processes on polycrystalline and heterogeneous graphene films require more advanced hyperspectral Raman capable of fast imaging at a high spatial resolution over hundreds of microns. Here, we compare the capacity of two different Raman imaging schemes (scanning and global) to probe graphene films modified by a low-pressure plasma treatment and present an analysis method providing assessments of the surface properties at local defects, grain boundaries, and other heterogeneities. By comparing statistically initial and plasma-treated regions of graphene, we highlight the presence of inhomogeneities after plasma treatment linked to the initial state of the graphene surface. These results provided statistical results on the correlation between the graphene initial state and the corresponding graphene-plasma interaction. This work further demonstrates the potential use of global hyperspectral Raman imaging with advanced Raman spectra analysis to study graphene physics and chemistry on a scale of hundreds of microns.

中文翻译：

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使用高光谱拉曼探测等离子体处理的石墨烯

拉曼光谱提供丰富的光信号，可在数据分析后用于评估石墨烯层是否原始、掺杂、损坏、功能化或受压。然而，传统拉曼光谱仪探测的区域受限于激光束的尺寸（~1 µm）；因此，石墨烯样品中不均匀性的详细映射需要在每个像素上缓慢且连续地获取拉曼光谱。对多晶和异质石墨烯薄膜的物理和化学过程的研究需要更先进的高光谱拉曼光谱，能够以超过数百微米的高空间分辨率进行快速成像。这里，我们比较了两种不同的拉曼成像方案（扫描和全局）探测通过低压等离子体处理改性的石墨烯薄膜的能力，并提出了一种分析方法，可评估局部缺陷、晶界和其他异质性的表面特性。通过比较石墨烯的统计初始和等离子体处理区域，我们强调了等离子体处理后与石墨烯表面初始状态相关的不均匀性的存在。这些结果提供了石墨烯初始状态与相应的石墨烯-等离子体相互作用之间相关性的统计结果。这项工作进一步证明了全球高光谱拉曼成像与高级拉曼光谱分析在数百微米尺度上研究石墨烯物理和化学的潜在用途。