Plasmon-assisted hot electron and Raman spectroscopy at the nanoscale

Plasmon-assisted hot electron and Raman spectroscopy at the nanoscale.​


​We present for the first time the simultaneous use of three complementary techniques to access the electronic transport, mechanical vibration and chemical homogeneity of a sample. These are Plasmonic assisted hot electron spectroscopy, Atomic force microscopy and Plasmonic assisted Raman Microscopy. Layer thickness, substrate defects and environmental doping influence deeply the nanoscale mechanical optical electronic properties of graphene and RGO and in general the growing family of the so-called 2D materials. For these reason their concurrent nanoscale mapping and their correlation with the samples morphology provides a powerful means of understanding and possibly controlling the all these influencing features. Here we report the mapped properties of the sample as topography, which can clearly discriminate between the different thicknesses and surface quality, the characteristic peak amplitude and shift in the Raman spectrum that identify univocally the layer number and chemical bonding structure, and the charge transport, that relates to the difference in the local electronic properties  being sensible to surface defects and domain interface. (Properties difficult to determine due to the qualitative nature of the macroscale technique). These techniques provide a straightforward identification of 2D metal domains with various thicknesses where the topographical determination is hindered by adsorbates and substrate terraces.

We report also Electrostatic Force Spectroscopy of the sample to​ determine the quantitative surface potential with high spatial resolution. Using these techniques, we guess we can investigate further the interaction evolution of the environmental water with the external layer as a function of temperature or humidity level, which determines generally a significant change of the absolute surface potential difference.