Our colleagues Branko Gumhalter and Dino Novko have published a monograph in a special volume of the journal Progress in Surface Science in which within the general framework of Interplay of electron-photon and electron-plasmon interactions at surfaces: Photonics and plasmonics in juxtaposition they had developed complementary perturbative and non-perturbative treatments of plasmonically induced electron emission from flat metal surfaces.

Complementary perturbative and nonperturbative pictures of plasmonically induced electron emission from flat metal surfaces

Branko Gumhalter, Dino Novko

Progress in Surface Science, 98, 3, 2023, 100706, DOI: 10.1016/j.progsurf.2023.100706

Many aspects of quantum nanotechnologies are associated with the phenomena that are the subject of photonics and plasmonics research. Underlying these phenomena are the electron-photon and electron-plasmon interactions in nanostructured systems. Each phenomenon is interesting and important in its own right, but of particular significance is their interplay as it opens new channels of controllable and explorable interactions on the nanoscale at the solid–solid, solid–vacuum, and solid-molecule interfaces. We report the results of research aimed at revealing, disentangling, identification and characterization of the components of this interplay in the simplest available model system for this purpose, i.e., a planar metal surface supporting surface-localized electronic bands. Towards this goal we have focused on the interpretation of high resolution multiphoton photoemission experiments on the (111), (110) and (100) atomically defined monocrystal silver surfaces. Their electronic structures provide versatile environments for photon- and plasmon-electron interactions, which are unraveled by energy, momentum, and time resolved detections of single electrons emitted through nonlinear two-photon absorption. Besides the standard photoemission signal, which scales with the energies of absorbed photons as prescribed by the generalized Einstein’s relation, experiments have also revealed the phenomenon of plasmoemission, i.e.  electron emission yields disobeying Einstein’s  relation with energy scaling solely with the multiples of plasmon energy. Generalizing the theory of multiphoton photoemission to plasmoemission we have successfully described the observed non-Einsteinian plasmoemission yields and thereby established a unified framework for interpretation of the two closely related photonic and plasmonic phenomena.