Scanning Electron Microscopy and X-Ray Microanalysis

V

Preface

This is not your father’s, your mother’s, or your
grandparent’s Scanning Electron Microscopy and
X-Ray Microanalysis (SEMXM). But that is not to
say that there is no continuity or to deny a family
resemblance. SEMXM4 is the fourth in the series of
textbooks with this title, and continues a tradition
that extends back to the “zero-th edition” in 1975
published under the title, “Practical Scanning
Electron Microscopy” (Plenum Press, New  York).
However, the latest edition differs sharply from its
predecessors, which attempted an encyclopedic
approach to the subject by providing extensive
details on how the SEM and its associated devices
actually work, for example, electron sources, lenses,
electron detectors, X-ray spectrometers, and so on.

In constructing this new edition, the authors have
chosen a different approach. Modern SEMs and the
associated X-ray spectrometry and crystallography
measurement functions operate under such exten-
sive computer control and automation that it is
actually difficult for the microscopist-microanalyst
to interact with the instrument except within care-
fully prescribed boundaries. Much of the flexibility
of parameter selection that early instruments pro-
vided has now been lost, as instrumental operation
functions have been folded into software control.
Thus, electron sources are merely turned “on,” with
the computer control optimizing the operation, or
for the thermally assisted field emission gun, the
electron source may be permanently “on.” The user
can certainly adjust the lenses to focus the image,
but this focusing action often involves complex
interactions of two or more lenses, which formerly
would have required individual adjustment. More-
over, the nature of the SEM field has fundamentally
changed. What was once a very specialized instru-
ment system that required a high level of training
and knowledge on the part of the user has become
much more of a routine tool. The SEM is now sim-
ply one of a considerable suite of instruments that
can be employed to solve problems in the physical
and biological sciences, in engineering, in technol-
ogy, in manufacturing and quality control, in fail-
ure analysis, in forensic science, and other fields.

The authors also recognize the profound changes
that have occurred in the manner in which peo-
ple obtain information. The units of SEMXM4,
whether referred to as chapters or modules, are
meant to be relatively self-contained. Our hope

is that a reader seeking specific information can

select a topic from the list and obtain a good

understanding of the topic from that module

alone. While each topic is supported by informa-

tion in other modules, we acknowledge the like-

lihood that not all users of SEMXM4 will “read

it all.” This approach inevitably leads to a degree

of overlap and repetition since similar informa-

tion may appear in two or more places, and this is

entirely intentional.

In recognition of these fundamental changes, the

authors have chosen to modify SEMXM4 exten-

sively to provide a guide on the actual use of the

instrument without overwhelming the reader with

the burden of details on the physics of the opera-

tion of the instrument and its various attachments.

Our guiding principle is that the microscopist-

microanalyst must understand which parameters

can be adjusted and what is an effective strategy to

select those parameters to solve a particular prob-

lem. The modern SEM is an extraordinarily flex-

ible tool, capable of operating over a wide range

of electron optical parameters and producing

images from electron detectors with different sig-

nal characteristics. Those users who restrict them-

selves to a single set of operating parameters may

be able to solve certain problems, but they may

never know what they are missing by not explor-

ing the range of parameter space available to them.

SEMXM4 seeks to provide sufficient understand-

ing of the technique for a user to become a com-

petent and efficient problem solver. That is not to

say that there are only a few things to learn. To

help the reader to approach the considerable body

of knowledge needed to operate at a high degree

of competency, a new feature of SEMXM-4 is the

summary checklist provided for each of the major

areas of operation: SEM imaging, elemental X-ray

microanalysis, and backscatter-diffraction crystal-

lography.

Readers familiar with earlier editions of SEMXM

will notice the absence of the extensive material

previously provided on specimen preparation.

Proper specimen preparation is a critical step in

solving most problems, but with the vast range of

applications to materials of diverse character, the

topic of specimen preparation itself has become

the subject of entire books, often devoted to just

one specialized area.