Chapter 2
Thin-Film Elemental Analyses for Precise Characterization of Minerals
Downloaded by GEORGETOWN UNIV on June 4, 2018 | https://pubs.acs.org Publication Date: November 29, 1990 | doi: 10.1021/bk-1990-0415.ch002
Ian D. R. Mackinnon Electron Microscope Centre, University of Queensland, St. Lucia QLD 4067, Australia
The A n a l y t i c a l Electron Microscope (AEM), with which secondary X-ray emission from a t h i n (11. Most S i ( L i ) EDS detectors provide an energy r e s o l u t i o n ranging from ~140eV to "*160eV depending upon the p a r t i c u l a r model detector, the manufacturer and degree of damage experienced by the detector over i t s l i f e t i m e . Energy resolution f o r EDS detectors i s usually measured as the full-width at half-maximum (FWHM) f o r the MnKa peak, and values less than 146eV FWHM at MnKa allow complete resolution of the K-lines f o r S i (1.74kV) and A l (1.49kV) [JL1]. Considerable overlap of these two peaks w i l l occur i f an energy resolution >165eV i s obtained. In the sections to follow, quantitative t h i n - f i l m analyses of minerals have been obtained with these Be-window s i ( L i ) EDS detectors with resolution generally better than 154eV. S i ( L i ) detectors without Be windows ("windowless") or with t h i n metal-coated polymer films (Ultra-Thin Window; UTW) have become an important peripheral to modern-day AEMs f o r the q u a l i t a t i v e detection of elements with 5
