论文标题
石墨烯同位素超晶格的真实空间拉曼光谱
Real Space Raman Spectroscopy of Graphene Isotope Superlattices
论文作者
论文摘要
我们报告了由化学蒸气沉积合成的12C/13C石墨烯同位素超级晶格的拉曼光谱。在很大程度上，拉曼光谱对应于批量12C和13C的贡献之和。但是，在较小的时期，我们观察到涉及两个声子的拉曼过程的混合12c/13c模式的形成，这导致2d和2d'拉曼峰的三倍。在真实空间拉曼光谱框架的框架内，可以很好地理解这种三倍，其中两个发出的声子源自超级晶格的不同区域。随着超晶格半周期接近光启用的电子孔对的平均自由路径，混合峰的强度增加。通过改变6至225 nm之间的超晶格周期，我们可以直接衡量光启用的电子平均自由路径，该路径的悬浮石墨烯为18 nm，对于SIO2底物上的石墨烯为7 nm。
We report the Raman spectroscopy of 12C/13C graphene isotope superlattices synthesized by chemical vapour deposition. At large periods the Raman spectra corresponds to the sum of the bulk 12C and 13C contributions. However, at small periods we observe the formation of mixed 12C/13C modes for Raman processes that involve two phonons, which results in the tripling of the 2D and 2D' Raman peaks. This tripling can be well understood in the framework of real space Raman spectroscopy, where the two emitted phonons stem from different regions of the superlattice. The intensity of the mixed peak increases as the superlattice half period approaches the mean free path of the photo-excited electron-hole pairs. By varying the superlattice period between 6 and 225 nm we have a direct measure of the photo-excited electron mean free path, which was found to be 18 nm for suspended graphene and 7 nm for graphene on SiO2 substrates.
