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Electron microscopy and X-ray microanalysis : key research tools in applied science

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Jablonski, Wis(Wieslaw) (1997) Electron microscopy and X-ray microanalysis : key research tools in applied science. Research Master thesis, University of Tasmania.

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Abstract

The diversity of the science of electron microscopy (EM) is difficult to
compare with any other instrument-supported science. Not only the
multitude of methods but also the variety of electron beam instruments
preclude a clear definition of the boundary of electron microscopy fields of
application and most likely it will touch and influence other branches of
science which are at first glance, unrelated to the subject.
This thesis is devoted to developments in electron microscopy and X-ray
microanalysis and their utilisation as key research tools in applied science.
The work presented here has been performed on various electron beam
instruments such as transmission electron microscopes (TEM), scanning
electron microscopes (SEM), scanning electron microscopes with X-ray
microanalytical attachments and dedicated electron probe microanalysers
(EPMA). The respective methods and techniques which have been
developed to satisfy the requirements of the general scientific community
are also presented.
This dissertation demonstrates the need for electron microscopy and
outlines the advantages of using new, customer-induced methods within
the campus of research institutions and beyond. Bearing in mind the
multidisciplinary aspects of electron microscopy, the development and
application of methods and techniques as presented in the following
chapters cover a vast area of interest. It can be said that practically almost
all branches of science may benefit from these in one way or another.
Developments presented here are divided into the results obtained within
the existing instrument configurations and the results procured after some
modifications and extensions of the existing EM instrument capabilities.
A new approach to the preparative techniques used to compensate for a
lack of more sophisticated and expensive associated equipment spells out possibilities of achieving the same results with a minimum of financial
outlay and maximum scientific gain. Some specimen modifications that
were achieved by an ion etching method show how to obtain more
information from a specimen which may be obscured by undesirable and
difficult to remove outer layers of biological or foreign origin.
In the field of X-ray microanalysis, suitability of standards is assessed by
calculating a mean atomic number of standards in relation to
microanalysed material. The same approach is used quantitatively to
estimate a backscattered electron coefficient and an atomic number
contrast in the phases of mineralogical samples. Experimental problems
with trace element analysis and interferences from major elements are
discussed and example of such a case is presented. The recipes are given
for quantitative analysis of light elements such as oxygen, carbon and
carbon-based synthetic materials (polymers). In the course of quantitative
analysis of oxygen it is demonstrated that in mineralogy, stoichiometry
may no longer be an ironclad guarantee. In some instances new
standards, specially for quantitative work on specimens of organic origin
are created, their usefulness is assessed and thoroughly examined for
homogeneity. Also, it becomes evident that the well described and easily
available polymers can be used as reliable standards in the light elements
analysis. For the first time low magnification phenomena in EPMA have been
investigated and quantified with the full benefit determined for a
minimum of specimen damage and electron optics contamination. Some
application programs have been written and their merits in the field of
microanalysis explained and presented in full in Appendices.
It is postulated that peak performance of an electron beam instrument
depends on many factors, some of which, e.g. contamination may be practically beyond control of the operator. Further, some means of
minimising the problems are provided.
It is also shown that a very recent introduction of an environmental SEM
(ESEM) is making a substantial impact on the conventional ways of
specimen preparation and observation and is providing a new insight into
X-ray microanalysis and related phenomena at elevated pressures (low
vacuum) in a specimen chamber.
The educational and aesthetic aspects of electron microscopy are
considered and the ways of efficient dissemination of electron microscopy
science are presented with special regard to computer-based and related
technologies.
Finally, certain procedures for successful assessment of a new electron
beam instrument and its purchase, based on the ESEM acquisition process
are recommended.

Item Type: Thesis (Research Master)
Copyright Holders: The Author
Copyright Information:

Copyright 1997 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
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Additional Information:

Examines the developments in electron microscopy and X-ray microanalysis, with work performed on various electron beam instruments, such as transmission electron microscopes, scanning electron microscopes, and electron probe microanalysers. Thesis (M.Sc.)--University of Tasmania, 1998. Includes bibliographical references. Examines the developments in electron microscopy and X-ray microanalysis, with work performed on various electron beam instruments, such as transmission electron microscopes, scanning electron microscopes, and electron probe microanalysers

Date Deposited: 19 Dec 2014 02:36
Last Modified: 31 Aug 2016 04:45
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