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Microcalorimeter EDS Measurements of Chemical Shifts in Fe Compounds

Published

Author(s)

David A. Wollman, Dale E. Newbury, Gene C. Hilton, Kent D. Irwin, L L. Dulcie, Norman F. Bergren, John M. Martinis

Abstract

Chemical shifts result from changes in electron binding energies with the chemical environment of atoms. In x-ray spectra, chemical shifts lead to changes in x-ray peak positions, relative peak intensities, and peak shapes. These chemical bonding effects can be significant (with x- ray peak shifts on the order of 1 eV), particularly for x-ray lines resulting from transitions involving valence electrons of light elements such as B and C. 1 Previously, chemical shifts in x-ray spectra have been measurable only using the high energy resolution of WDS. Recently, we have developed a microcalorimet er EDS 2,3 with an instrument- response energy resolution of ~4 eV FWHM (real-time analog processing) over the energy range from 0 keV to ~2 keV. This energy resolution is comparable to that of a WDS and for the first time is sufficient to allow EDS chemical shift measurements. In this work, x-ray spectra of flat, polished Fe compounds (Fe, FeO-OH, Fe2O3, Fe 3O4, FeS, and FeS2) were acquired using a microcalorimet er EDS mounted on a commercial scanning electron microscope (SEM) column. Two representative microcalorimeter EDS spectra (Fe and FeO-OH) are shown in Fig. 1. Heat pulses were injected into the microcalorimeter at regular intervals and recorded as part of each x-ray spectrum. The resulting heat pulse peak position was monitored to ensure constant detector gain for different spectra.
Proceedings Title
Proc., Microscopy and Microanalysis Conf.
Conference Dates
July 12-16, 1998
Conference Location
Atlanta, GA

Citation

Wollman, D. , Newbury, D. , Hilton, G. , Irwin, K. , Dulcie, L. , Bergren, N. and Martinis, J. (1998), Microcalorimeter EDS Measurements of Chemical Shifts in Fe Compounds, Proc., Microscopy and Microanalysis Conf., Atlanta, GA (Accessed February 28, 2024)
Created July 1, 1998, Updated June 17, 2020