Local and Global Directionality Patterns of Electron Photoemission from Plasmonic Nanoparticles

Concepts of local and global photoemission directivity patterns are introduced for plasmonic nanoparticles of arbitrary shape, and the relationship between them is established. Formulas for the local photoemission directionality pattern for surface and volume photoemission mechanisms are obtained for a given field distribution in plasmonic modes inside nanoparticles of arbitrary shape. As an illustration of the theory, the local and global photoemission patterns are calculated for spherical nanoparticles with excited dipole or quadruple plasmonic modes. It is shown that the patterns resulting from the surface and volume photoemission differ qualitatively as well as the patterns produced by various plasmonic modes. The findings can be useful in various plasmonic applications, namely, nanostructured photocathodes, photodetectors, in plasmonic photocatalysis, and others.