Imaging a Photon

When photons (light) interact with silver or gold particles, they can excite the electrons in the metal, and this leads to electric fields near the particles which are temporarily enhanced. Scientists at Northwestern University, working in collaboration with Argonne National Laboratory, and a French group, have developed a method for observing images of this electric field, and therefore of the photon. In this image, the enhanced fields are used to excite molecules in a polymer coating near the particles, and this results in periodic restructuring of the polymer that is easily measured with an atomic force microscope (AFM).

Figure 1. Schematic of polymer deposition on triangular silver nanostructures.

Figure 2. AFM images of the polymer after irradiation, including periodic structuring of the polymer that arises from interaction of the nanoparticles with photons.