ALCHEMI: a new technique for locating atoms in small crystals

摘要: 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 few hundred Angstroms impurity concentrations down about 0·1 atomic per cent. It capable distinguishing neighbours periodic table. uses incident electron beam orientation dependence characteristic X-ray emission an energy dispersive microanalyser fitted transmission microscope. does not require specimen thickness or precise known, makes assumptions form dynamical wavefunction, which need calculated predicted. classical problems cation ordering spinels, feldspars olivine have now been studied this method.