Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy

A novel form of microscopy has been used to map the field dynamics of surface plasmon resonances. Hiroaki Misawa and co-workers in Japan used high-resolution (10 nm) multiphoton photoemission electron microscopy (MP-PEEM) to image the field distribution of a variety of metallic nanostructures, such as arrays of gold rods, nanodisks and dimer pairs. MP-PEEM works by recording the electrons emitted from a sample in response to illumination with a series of ultrashort pulses. Illumination with near-infrared pulses caused excited plasmon resonances in the gold nanostructures to show up in the resulting MP-PEEM images as local hot spots, from which the field distribution was determined. The short duration of the pulses made it possible to probe the dynamics of the plasmon resonance field distribution on the femtosecond timescale.