The electronic structure and structural evolution of hydrogenated graphene are investigated by Raman spectroscopy with multiple excitations. The excitation energy dependent saturation effect on the ratio of integrated intensities of D and G modes (ID/IG) is revealed and further developed as a quick method for estimation of inter-defect distance and defect density in hydrogenated graphene. At low hydrogen coverage, the chemisorbed H atoms behave like defects in sp2 C=C matrix; while for a high hydrogen coverage, the sp3 C-H bonds become coalescent clusters, resulting in confinement effect on the sp2 C domains. Electronic structure changes caused by varying hydrogen coverage are evidenced by excitation energy dependent red shift of D and 2D bands. Our results provide a useful guide for developing applications of hydrogenated graphene, as well as using Raman spectroscopy as quick metrology of the defect density in further exploring other kinds of graphene derivatives.
@article{arxiv.1009.0091,
title = {Electronic Structure and Structural Evolutions of Hydrogenated Graphene Probed by Raman Spectroscopy},
author = {Zhiqiang Luo and Ting Yu and Zhenhua Ni and Sanhua Lim and Jingzhi Shang and Hailong Hu and Lei Liu and Zexiang Shen and Jianyi Lin},
journal= {arXiv preprint arXiv:1009.0091},
year = {2010}
}