Microscopy and Microanalysis



Instrumentation and Technique

Automated Analysis of SEM X-Ray Spectral Images: A Powerful New Microanalysis Tool


Paul G.  Kotula  a1 c1, Michael R.  Keenan  a1 and Joseph R.  Michael  a1
a1 Materials Characterization Department, Sandia National Laboratories, P.O. Box 5800, MS 0886, Albuquerque, NM 87185-0886, USA

Abstract

Spectral imaging in the scanning electron microscope (SEM) equipped with an energy-dispersive X-ray (EDX) analyzer has the potential to be a powerful tool for chemical phase identification, but the large data sets have, in the past, proved too large to efficiently analyze. In the present work, we describe the application of a new automated, unbiased, multivariate statistical analysis technique to very large X-ray spectral image data sets. The method, based in part on principal components analysis, returns physically accurate (all positive) component spectra and images in a few minutes on a standard personal computer. The efficacy of the technique for microanalysis is illustrated by the analysis of complex multi-phase materials, particulates, a diffusion couple, and a single-pixel-detection problem.

(Received November 6 2001)
(Accepted June 5 2002)


Key Words: spectrum image; spectral image; statistical analysis; principal components analysis; X-ray microanalysis; information extraction; multivariate statistical analysis.

Correspondence:
c1 Corresponding author. E-mail: pgkotul@sandia.gov