Electron rescattering in photoemission from metal tips as a nanoscale probe of near-field enhancement

In the vicinity of nanostructures, the electric field strength of optical and infrared radiation is significantly enhanced. This near-field enhancement allows the localization of electromagnetic energy on a sub-wavelength scale (Fig. 1(a)). Because of the nanometric length scale, the coupling of light and matter, and the often unknown exact shape of the nanostructure in question, measuring and simulating optical near-fields has proven hard.