Abstract: A Surface Plasmon Scanning-Tunneling Chemical Mapping (SPSTM) system is disclosed that determines identification characteristics of a target material. An optical beam source launches an optical beam that propagates through a transparent optical element to a material layer to excite surface plasmons of the material layer. An optical probe with a nanometer-sized tip is positioned over a nanometer-sized region of the target material, which is positioned on the material layer, to measure a probe signal associated only with the surface plasmons that tunnel from the material layer through the nanometer-sized region of the target material and collected by the optical probe. An optical property analyzer is configured to determine at least one optical property associated with the nanometer-sized region based on the probe signal associated with the surface plasmons collected by the optical probe.