Surface plasmon near-field back-action and displacement of enhanced Raman scattering spectrum in graphene

It has been recently observed that plasmonic nanoantennas tuned to the Stokes wavelengths associated with the G and 2D Raman bands of graphene, rather than the laser pump, not only enhance Raman scattering in graphene but also displace and broaden the Raman spectra Ghamsari et al (2015 Phys. Rev. B 91 201408(R)). This paper presents a model to explain the frequency pulling and lineshape broadening effects based on the back-action of surface plasmons near-field on the induced microscopic Raman dipoles in graphene. The model provides the relation among Raman enhancement factor, Raman frequency displacement, and broadening caused by Stokes-tuned resonant nanoantennas and compares the results to the previously reported experimental data. (paper)