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Defocus image contrast in hexagonally-ordered mesoporous material
Nakahara, Shohei; Tanner, David A.; Hudson, D.A; Magner, S; Redington, E; Hodnett, Benjamin K.
A transmission electron microscope was used to characterize a powder form of hexagonally-ordered mesoporous silica material. The structural symmetry built into this amorphous material allowed one to obtain three characteristic images, i.e. a hexagonal honey-comb structure and wide/narrow parallel lines. These images were found to originate primarily from phase contrast, which changed sensitively with defocusing. To further understand the contrast behaviour of these images, an analytical form of the defocus contrast theory was developed and applied to the simulation of the characteristic wide/narrow parallel line images. The simulation was found to be in good qualitative agreement with experiments, where changes in focus conditions and specimen thickness were predicted to alter the contrast in the resulting parallel-line type images. PUBLISHED peer-reviewed
Keyword(s): transmission electron-microscopy; molecular-sieves; silica; SBA-15; films; tomography; adsorption
Publication Date:
2011
Type: Journal article
Peer-Reviewed: Yes
Language(s): English
Institution: University of Limerick
Citation(s): Royal Chemistry Chemical Physics;Jan, 21, 13(3), pp. 1189-1200
Publisher(s): Royal Society of Chemistry
First Indexed: 2013-12-06 05:30:55 Last Updated: 2018-12-15 07:01:22