Microcalorimeter EDS Measurements of Chemical Shifts in Fe Compounds

Published

July 1, 1998

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

Pub Type

Conferences

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 July 17, 2024)