High-Resolution Electron-Energy Loss Spectroscopy (HR-EELS)

HR-EELS is a powerful tool to probe any kind of excitations that emerge in a solid crystal such as plasmon, phonon, inter- & intra-band transition, and local vibrations. HR-EELS technique makes use of inelastic scattering of incident electrons with an energy of 5 ~ 200 eV with an optimal energy resolution of less than 0.5 meV, which exchange energy with the excitations.

Recent HR-EELS studies focusses on low-dimensional (1D) collective excitations, such as two-dimensional (2D) collective excitations of Dirac fermions, charge excitations in quasi-one-dimensional atomic chain, and topological properties of phonons.

A schematic of EELS with a mono-chromater and analyzer

The plasmon excitations provide experimental evidences of (left) the Tomonaga-Luttinger liquid behavior in a quasi-1D system, In/Si(111)-4x1, and (right) the survival of Dirac fermionic plasmon throughout the single-particle excitation regime in a prototypical 2D system, graphene.

Electronic correlations, such as a Mott-Hubbard type insulating phase and charge density waves, are observed as an energy gap in the HR-EELS spectra.

  1. Physical Review B 83, 161403(R) (2011)

  2. Journal of the Korean Physical Society 53, 3667 (2008)

  3. Surface Science 602, 2300 (2008)

  4. New Journal of Physics 10, 053013 (2008)

  5. Journal of the Korean Physical Society 53, 1065 (2008)

  6. New Journal of Physics 9, 249 (2007)

  7. Journal of Physics: Conference Series 61, 454 (2007)

  8. Surface Science 516, L529 (2002)

  9. Physical Review Letters 88, 196401 (2002)

  10. Physical Review Letters 84, 1748 (2000)