Nanoscale probing of resonant photonic modes in dielectric nanoparticles with focused electron beams

Qianlang Liu, Steven C. Quillin, David J. Masiello, Peter A. Crozier

Research output: Contribution to journalArticle

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Abstract

Understanding the optical responses of nanostructures with high spatial resolution is paramount in photonic engineering. The excitation of resonant optical-frequency geometric modes in oxide nanoparticles is explored using monochromated electron energy-loss spectroscopy in a scanning transmission electron microscope. These geometric or cavity modes are found to produce a progression of resonance peaks within the bandgap regions of the electron energy-loss spectra of CeO2, TiO2, and MgO nanoparticles. Complementary simulations of the electron probe combined with analytic Mie analysis are performed to interpret the complex spectral features and to understand their underlying physical origins. The factors that influence the energies, shapes, and strengths of these modes are also investigated and their dependence upon nanoparticle size, geometry, refractive index, aggregation, impact parameter, and electron kinetic energy are elucidated. Taken together, this work demonstrates the unique ability of fast electron spectroscopy to determine the photonic density of states in individual and complex assemblies of dielectric nanoparticles.

Original languageEnglish (US)
Article number165102
JournalPhysical Review B
Volume99
Issue number16
DOIs
StatePublished - Apr 3 2019

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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