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Spatially Resolved Energy Electron Loss Spectroscopy Studies of Iron Oxide Nanoparticles

Published online by Cambridge University Press:  23 August 2006

Jacek Jasinski ,
Kent E. Pinkerton ,
I.M. Kennedy  and
Valerie J. Leppert
Jacek Jasinski
Affiliation:
School of Engineering, University of California, Merced, CA 95344, USA
Kent E. Pinkerton
Affiliation:
Center for Health and the Environment, University of California, Davis, CA 95616, USA
I.M. Kennedy
Affiliation:
Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616, USA
Valerie J. Leppert
Affiliation:
School of Engineering, University of California, Merced, CA 95344, USA
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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 L3 /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.

Keywords

EELSSTEMnanoprobenanoparticlesiron oxideionization edgeswhite linesoxidation state
Type
MICROANALYSIS
Information
Microscopy and Microanalysis , Volume 12 , Issue 5 , October 2006 , pp. 424 - 431
Copyright
© 2006 Microscopy Society of America

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References

REFERENCES

Botton, G.A., Appel, C.C., Horsewell, A., & Stobbs, W.M. (1995). Quantification of the EELS near-edge structures to study Mn doping in oxides. J Micros 180, 211–216.Google Scholar
Colliex, C., Manoubi, T., & Ortiz, C. (1991). Electron-energy-loss-spectroscopy near-edge fine-structures in the iron-oxygen system. Phys Rev B 44, 11402–11411.Google Scholar
Egerton, R.F. (1996). Electron Energy Loss Spectroscopy in the Electron Microscope, 2nd ed. New York and London: Plenum Press.
Krivanek, O.L. & Paterson, J.H. (1990). ELNES of 3d transition-metal oxides. 1. Variations across the periodic-table. Ultramicroscopy 32, 313–318.Google Scholar
Leapman, R.D. & Grunes, L.A. (1980). Anomalous L3-L2 white-line ratios in the 3d transition-metals. Phys Rev Lett 45, 397–401.Google Scholar
Leapman, R.D., Grunes, L.A., & Fejes, P.L. (1982). Study of the L23 edges in the 3d transition-metals and their oxides by electron-energy-loss spectroscopy with comparisons to theory. Phys Rev B 26, 614–635.Google Scholar
Mavrocordatos, D. & Perret, D. (1998). Quantitative and qualitative characterization of aquatic iron oxyhydroxide particles by EF-TEM. J Microsc 191, 83–90.Google Scholar
Otten, M.T., Miner, B., Rask, J.H., & Buseck, P.R. (1985). The determination of Ti, Mn and Fe oxidation-states in minerals by electron energy-loss spectroscopy. Ultramicroscopy 18, 285–289.Google Scholar
Paterson, J.H. & Krivanek, O.L. (1990). ELNES of 3d transition-metal oxides. 2. Variations with oxidation-state and crystal-structure. Ultramicroscopy 32, 319–325.Google Scholar
Pearson, D.H., Fultz, B., & Ahn, C.C. (1988). Measurements of 3d state occupancy in transition-metals using electron-energy loss spectrometry. Appl Phys Lett 53, 1405–1407.Google Scholar
Prasad, P.N. (2004). Nanophotonics. New York: John Wiley & Sons.
Rask, J.H., Miner, B.A., & Buseck, P.R. (1987). Determination of manganese oxidation-states in solids by electron energy-loss spectroscopy. Ultramicroscopy 21, 321–326.Google Scholar
Sparrow, T.G., Williams, B.G., Rao, C.N.R., & Thomas, J.M. (1984). L3/L2 white-line intensity ratios in the electron energy-loss spectra of 3d transition-metal oxides. Chem Phys Lett 108, 547–550.Google Scholar
van Aken, P.A., Liebscher, B., & Styrsa, V.J. (1998a). Core level electron energy-loss spectra of minerals: Pre-edge fine structures at the oxygen K-edge. [Comment on “Water in minerals detectable by electron energy-loss spectroscopy EELS” by R. Wirth (1997). Phys. Chem. Minerals 24, 561–568.] Phys Chem Miner 25, 494–498.Google Scholar
van Aken, P.A., Liebscher, B., & Styrsa, V.J. (1998b). Quantitative determination of iron oxidation states in minerals using Fe L2,L3-edge electron energy-loss near-edge structure spectroscopy. Phys Chem Miner 25, 323–327.Google Scholar
Waddington, W.G., Rez, P., Grant, I.P., & Humphreys, C.J. (1986). White lines in the L2,3 electron-energy-loss and X-ray absorption-spectra of 3d-transition metals. Phys Rev B 34, 1467–1473.Google Scholar
Wallis, D.J., Browning, N.D., Megaridis, C.M., & Nellist, P.D. (1996). Analysis of nanometre-sized pyrogenic particles in the scanning transmission electron microscope. J Microsc 184, 185–194.Google Scholar
Wang, Z.L. (2003). New developments in transmission electron microscopy for nanotechnology. Adv Mater 15, 1497–1514.Google Scholar
Zhou, Y.M., Zhong, C.Y., Kennedy, I.M., Leppert, V.J., & Pinkerton, K.E. (2003). Oxidative stress and NFkB activation in the lungs of rats: A synergistic interaction between soot and iron particles. Toxicol Appl Pharm 190, 157–169.Google Scholar