Strong polarization dependence of double-resonant Raman intensities in graphene.

Yoon, Duhee; Moon, Hyerim; Son, Young-Woo; Park, Bae Ho; Kim, Jin Bae; Lee, Youngpak; Cheong, Hyeonsik · Nano Lett · 2008

basic_science · Level V

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Abstract

Spatially resolved and polarized micro-Raman spectroscopy on microcrystalline graphene shows strong polarization dependences of double-resonance Raman intensities. The Raman intensity of the double-resonant 2D band is maximum when the excitation and detection polarizations are parallel and minimum when they are orthogonal, whereas that of the G band is isotropic. A calculation shows that this strong polarization dependence is a direct consequence of inhomogeneous optical absorption and emission mediated by electron-phonon interactions involved in the second-order Stokes-Stokes Raman scattering process.