Experimental identification of the out-of-plane phonon mode of a few layered graphene from individual Au nanoparticle-Au film junctions

Abstract

We can experimentally identify the layer-layer breathing mode and the other out-of-plane transverse acoustic phonon modes of a few layered graphene via employing z-polarized incident field formed at Au nanoparticle-Au film junctions. The observed out-of-plane mode phonon at ∼150 cm−1 and other transverse acoustic phonon type defect modes from 300 cm−1 to 700 cm−1 can be readily explored. Not only for the normally used optical method using focused plane wave but also direct applying the z-directional electromagnetic field on graphene will be expected for more detailed out-of-plane phonon characterization of graphene.