Figure 3
The experimental arrangement. (a) The sketch of the spectrometer which consists of a tip-sample system and a toroidal electron energy analyzer (TEEA). (b) The enlarged part of the tip-sample area. A tungsten tip is approached to a distance of micrometers from the sample surface, which is prepared by evaporating about 30 nm thick Au on HOPG. Au nanostructures can be observed in the topography image as shown in the inset. A negative voltage of hundred volts is applied to the tip while keep the sample surface grounded to produce field-emission electrons. The localized surface plasmon resonance of the Au nanostructures is excited by the field-emission electrons and the backscattered electrons are collected and energy-analyzed by a TEEA.
