Spatially resolved energy electron loss spectroscopy studies of iron oxide nanoparticles

Jacek Jasinski, Kent E Pinkerton, I. M. Kennedy, Valerie J. Leppert

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The oxidation state of iron oxide nanoparticles co-generated with soot during a combustion process was studied using electron energy-loss spectroscopy (EELS). Spatially resolved EELS spectra in the scanning transmission electron microscopy mode were collected to detect changes in the oxidation state between the cores and surfaces of the particles. Quantification of the intensity ratio of the white lines of the iron L-ionization edge was used to measure the iron oxidation state. Quantitative results obtained from Pearson's method, which can be directly compared with the literature data, indicated that the L 3/L2-intensity ratio for these particles changes from 5.5 ± 0.3 in the particles' cores to 4.4 ± 0.3 at their surfaces. This change can be directly related to the reduction of the iron oxidation state at the surface of the particles. Experimental results indicate that the cores of the particles are composed of γ-Fe2O3, which seems to be reduced to FeO at their surfaces. These results were also supported by the fine structure of the oxygen K-edge and by the significant chemical shift of the iron L-edge.

Original languageEnglish (US)
Pages (from-to)424-431
Number of pages8
JournalMicroscopy and Microanalysis
Volume12
Issue number5
DOIs
StatePublished - Oct 2006

Keywords

  • EELS
  • Ionization edges
  • Iron oxide
  • Nanoparticles
  • Nanoprobe
  • Oxidation state
  • STEM
  • White lines

ASJC Scopus subject areas

  • Instrumentation

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