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ALCHEMI: a new technique for locating atoms in small crystals
Author(s) -
Spence J. C. H.,
Taftø J.
Publication year - 1983
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1983.tb04213.x
Subject(s) - channelling , impurity , atom (system on chip) , electron , orientation (vector space) , angstrom , crystal (programming language) , transmission electron microscopy , atomic physics , materials science , crystallography , chemistry , physics , nanotechnology , geometry , nuclear physics , ion , mathematics , organic chemistry , computer science , embedded system , programming language
SUMMARY Atom Location by Channelling Enhanced Microanalysis (ALCHEMI) is a quantitative technique for identifying the crystallographic sites, distribution and types of substitutional impurities in many crystals. The method involves no adjustable parameters, can be applied to areas as small as a few hundred Angstroms and to impurity concentrations down to about 0·1 atomic per cent. It is capable of distinguishing neighbours in the periodic table. The method uses the incident electron beam orientation dependence of characteristic X‐ray emission and uses an energy dispersive X‐ray microanalyser fitted to a transmission electron microscope. The method does not require the specimen thickness or precise orientation to be known, and makes few assumptions about the form of the dynamical electron wavefunction, which need not be calculated or predicted. The classical problems of cation ordering in spinels, feldspars and olivine have now been studied by this method.