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Improved spatial resolution microanalysis in a scanning transmission electron microscope
Author(s) -
Faulkner R. G.,
Hopkins T. C.,
Norrgård K.
Publication year - 1977
Publication title -
x‐ray spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.447
H-Index - 45
eISSN - 1097-4539
pISSN - 0049-8246
DOI - 10.1002/xrs.1300060205
Subject(s) - microanalysis , microscope , optics , scanning transmission electron microscopy , materials science , resolution (logic) , acceleration voltage , conventional transmission electron microscope , scanning electron microscope , transmission electron microscopy , image resolution , electron beam induced deposition , electron , analytical chemistry (journal) , cathode ray , chemistry , physics , organic chemistry , chromatography , quantum mechanics , artificial intelligence , computer science
The attachment of energy‐dispersive analysers to scanning transmission electron microscopes makes possible accurate high spatial resolution microanalysis. This paper quantifies the X‐ray spatial resolution obtainable for good sensitivity microanalysis as a function of microscope lens settings and primary electron beam accelerating voltage in a 200 k V scanning transmission electron microscope. It is shown that at 200 k V a resolution of approximately 500 Å is possible with a 1500 Å thick nickel–iron–chromium alloy specimen. At 100 k V the resolution drops to nearer 1000 Å These figures are supported by Monte Carlo calculations of electron trajectories in thin films. Comparisons of experimentally measured and theoretically predicted X‐ray intensities suggest a severe loss of signal intensity within the microscope; this loss becomes greater at higher accelerating voltages. The influence on microanalysis of angle of specimen inclination to beam and to the detector is considered and precautions necessary to limit beam drift during 1000 s analyses are discussed. The application of high sensitivity, high resolution microanalysis methods to a grain boundary segregation effect in an austenitic creep resistant steel is described. It is shown that titanium segregates in a zone 1000–1500 Å thick on either side of the grain boundary to a level of approximately three times the matrix concentration.