Structural Raman Enhancement in Graphite Nano-Discs

Paper in proceedings, 2016

Raman scattering in disc-shaped graphite nanostructures, etched out of bulk HOPG, are investigated using an excitation wavelength of 532 nm at different laser power. The G-band is fitted using two Lorentzian functions, G(L) and G(H). The difference of Raman shift between the two Lorentzian functions increase with laser power as a consequence of selective absorption and heating of the discs. Further, the G-band from the nanostructured HOPG reveal a Raman enhancement (R-E) of similar to 2.2 and similar to 1.5 for the components associated with the discs (G(L)) and the supporting substrate (G(H)), respectively. The quantitative agreement between the experimental results and performed finite difference time domain calculations make possible to conclude that electromagnetic energy penetrates considerably into the discs from the circular periphery probably due to multiple scattering. In addition, the dependence of R-E of the G(L) component on the laser power is attributed to a temperature dependent electron-phonon coupling.