Excited-state imaging of single particles on the subnanometer scale

Alison Wallum, Huy A. Nguyen, Martin Gruebele

Research output: Contribution to journalReview articlepeer-review


At the intersection of spectroscopy and microscopy lie techniques that are capable of providing subnanometer imaging of excited states of individual molecules or nanoparticles. Such approaches are particularly important for imaging macromolecules or nanoparticles large enough to have a high probability of containing a defect. These inevitable defects often control properties and function despite an otherwise ideal structure. We discuss real-space imaging techniques such as using scanning tunneling microscopy tips to enhance optical measurements and electron energy-loss spectroscopy in a scanning transmission electron microscope, which is based on focused electron beams to obtain high-resolution spatial information on excited states. The outlook for these methods is bright, as they will provide critical information for the characterization and improvement of energy-switching, electron-switching, and energy-harvesting materials.

Original languageEnglish (US)
Pages (from-to)415-433
Number of pages19
JournalAnnual Review of Physical Chemistry
StatePublished - Apr 20 2020


  • Raman spectroscopy
  • electron microscopy
  • excited state
  • scanning tunneling microscopy
  • super-resolution microscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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