Disentangling Cathodoluminescence Spectra in Nanophotonics: Particle Eigenmodes vs Transition Radiation

Saskia Fiedler, P. Elli Stamatopoulou, Artyom Assadillayev, Christian Wolff, Hiroshi Sugimoto, Minoru Fujii, N. Asger Mortensen, Søren Raza*, Christos Tserkezis*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Cathodoluminescence spectroscopy performed in an electron microscope has proven a versatile tool for analyzing the near- and far-field optical response of plasmonic and dielectric nanostructures. Nevertheless, the transition radiation produced by electron impact is often disregarded in the interpretation of the spectra recorded from resonant nanoparticles. Here we show, experimentally and theoretically, that transition radiation can by itself generate distinct resonances that, depending on the time-of-flight of the electron beam inside the particle, can result from constructive or destructive interference in time. Superimposed on the eigenmodes of the investigated structures, these resonances can distort the recorded spectrum and lead to potentially erroneous assignment of modal characters to the spectral features. We develop an intuitive analogy that helps distinguish between the two contributions. As an example, we focus on the case of silicon nanospheres and show that our analysis facilitates the unambiguous interpretation of experimental measurements on Mie-resonant nanoparticles.
Original languageEnglish
JournalNano Letters
Volume22
Issue number6
Pages (from-to)2320-2327
ISSN1530-6984
DOIs
Publication statusPublished - 2022

Keywords

  • Cathodoluminescence
  • Electron-beam spectroscopy
  • Dielectric nanoparticles
  • Mie resonances
  • Mode characterization
  • Transition radiation

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