Investigation of out-of-plane structural properties of a graphene monolayer with gap-plasmons: mode-selective Raman enhancement and the influence of additional sp~3 type defects

摘要

We report that Raman enhancements of a graphene monolayer sandwiched at the Au nanoparticle-Au thin film junction are different and can be attributed to the influence of a z-polarized incident field. Closer to the center of the junction, radial breathing like-mode (RBLM) shows dramatic Raman enhancement in terms of the coincidence between the z-polarized incident field formed at the junction and the RBLM phonon axis. The appearance of an additional D* peak can be identified and is attributed to the additional out-of-plane sp3 type defect signal. Correlating /(D*)//(D) with RBLM intensity variation further substantiates that the observed D* peak is ascribed to another out-of-plane structural defect signal.