Cherenkov Effect in the Context of Scanning Tunneling Microscopy

Abstract

The intensity of the light emission from the STM tunneling junction between two metals is shown to depend exponentially on the tunneling distance. Assuming the exponential decay constant to be equal to the mean wave vector of the surface plasmons excited by the tunneling electrons, the plasmon phase velocity is estimated to be two times smaller than the Fermi velocity of the electrons. A new theoretical description of the light emission phenomenon based on a Cherenkov-like resonant interaction between the tunneling electrons and the surface plasmons is developed. npOAeMOHCTpHpOBaHa 3KCnOHeHL(HaJIbHaX 3aBHCAMOCTb UHTeHCHBHOCTU CBeTa U3 TYHHeJIbHOrO KOHTaKTa CTM OT BeJIAWiHbI TyHHeJIbHOrO 3a30pa. npeAn0JIOraX IIOKa3aTeJIb 3KCnOHeHTbI PaBHbIM CpenHeMy BOJIHOBOMY BeKTOpy IIOBepXHOCTHblX nJIa3MOHOB, IlOJIyreHa OUeHKa UX @a30908 CKOPOCTH. @a30BaX CKOPOCTb B nBa pa3a MeHbLIIe @epMHeBCKO% CKOPOCTH 3JIeKTpOHOB B 30JIOTe. Pa3B11T HOBbI8 IIOAXOAK TeOpeTMWCKOMy OnMCaHMH3 U3JIyYeHHXCBeTa 113 TYHHeJIbHOrO KOHTaKTa Ha 6a3epe30HaHC-HOrO B3aHMOH&CTBUX TyHHeJIHpjTOLWiX 3JIeKTpOHOB C IlOBePXHOCTHbIMH rIJIa3MOHaMH, IIOAO6HOrO 3@@eKTY YepeHKOBa. ') Pontoppidanstraede 103, DK-9220 Aalborg Oest, Denmark. ' ) On leave from the Institute of Spectroscopy, Russian Academy of Sciences, 142092 Troitsk, Moscow obl., Russia. 18'

Light emission from gold and silver thin films in a scanning tunneling microscope: role of contamination and interpretation of grain structure in photon maps

“…The clear implication is that there is a lower workfunction and therefore a contamination layer on the Au sample (and tip) in atmosphere. Later, Smolyaninov and Keller [39], in further analysis of experimental data, revealed that the measured light emission depends exponentially on the tip-sample gap, d, and can be expressed in the form:…”

Photon Emission at Step Edges of Single Crystalline Gold Surfaces Investigated by Scanning Tunnelling Microscopy

“…Increasing the tunnel gap heavily penalises the emission efficiency since the coupling to LSPs falls off exponentially. 14,15) Case F. This is the converse to situation B and generally no enhancement is observed. The enhanced scattering that might be anticipated when x < R LSP is offset by the fact that the scattering feature, the inside edge of a step, is optically lossy metallic material.…”