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Bidirectional shadowing in freeze‐etching
Author(s) -
Willison J. H. M.,
Moir R. D.
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.tb04269.x
Subject(s) - materials science , particle (ecology) , etching (microfabrication) , rotation (mathematics) , shadow (psychology) , optics , casting , composite material , physics , geometry , mathematics , psychology , oceanography , layer (electronics) , psychotherapist , geology
SUMMARY Bidirectional shadowing in freeze‐etching may be achieved by firing an electron‐beam shadowing source, rotating the specimen stage through a desired angle, and re‐firing the shadowing source. It is demonstrated that portrait shadow‐casting, which permits information to be drawn from much of the specimen region lying within primary shadows, can be readily achieved using a 90° specimen rotation. With 180° specimen rotation, particle‐size analysis is feasible. Particle‐height analysis is demonstrated using membrane‐associated particles as an example. Data from suitable sets of micrographs can also be used for the estimation of particle‐width exaggeration due to the accumulation of the shadowing‐metal cap. Fibre‐width analysis, using the linear regression method, is demonstrated by a study of native cellulosic microfibrils. Mean microfibril widths were found to be 5.5–7.0 nm.