Plasmonic Photoemission from Single-Crystalline Silver

• DOI: 10.1021/acsphotonics.0c01412
• Publication Date: 2021-01-13T05:50:33Z
• Authors: Andi Li; Marcel Reutzel; Zehua Wang; Dino Novko; Branko Gumhalter; Hrvoje Petek
• Keywords: Attosecond; Free electron model; Photon energy

Optical fields interacting with solids excite single particle quantum transitions and elicit collective screening responses that define their penetration, absorption, reflection. The interplay of these interactions on the attosecond time scale defines how optical energy transforms to electronic, setting limits efficiency for processes such as solar harvesting or photocatalysis. Our understanding light–matter is primarily based specifying electronic structure initial particles occupying well-defined states, outcome interaction culminating in photoelectron photon emission analysis, scant ability follow transitional, ultrafast many-body it. properties metals transubstantiate from metallic dielectric when real part response function, Re[ε(ω)], passes through zero: at low frequencies, Re[ε(ω)] < 0, free electron plasmonic confers high reflectivity; > penetrate charge-density longitudinal plasmon waves. How decay femtosecond into excitations cardinal plasmonics, but not sufficiently well described by experiment theory. We examine spectroscopic signatures nonlinear index crystals silver two-photon photoemission spectroscopy, frequencies where bulk zero. find transition zero region reflected spectra, particular, plasmons giving rise a non-Einsteinian component. This response, photoelectrons defined incoming photons, occurs photons plasmons, which then exciting selectively Fermi level. Such mode hot electrons contrary general agreement, confirms theoretical prediction J. Hopfield 1965. illuminates more efficient optical-to-electronic flow so far has escaped scrutiny.