American Chemical Society, Journal of Physical Chemistry C, 5(115), p. 1422-1427, 2011
DOI: 10.1021/jp107109h
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The electronic structures 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 interpreted by a D band active model with D band Raman relaxation length and photoexcited electron/hole wavelength as critical length scales. At low hydrogen coverage, the chemisorbed H atoms behave like defects in sp2 C═C matrix; 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 for using Raman spectroscopy for quick characterization in further exploring other kinds of graphene derivatives.