FEI Quanta FEG 250, Руководство пользователя

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System Options: Energy Dispersive X-ray (EDX) Analysis
9-18
Energy Dispersive X-ray (EDX) Analysis
The EDX (sometimes referred to also as EDS analysis) is a technique
used for identifying the elemental composition of the specimen, or an
area of interest thereof. It works as an integrated feature of a scanning
electron microscope (SEM), and cannot operate on its own without
the latter.
The specimen is bombarded with an electron beam inside the
microscope column. These electrons collide with the specimen atoms'
own electrons, knocking some of them off in the process. Positions
vacated by ejected inner shell electrons are occupied by a higher-
energy electron from an outer shell, while giving up some of its energy
by emitting an X-ray. The amount of energy released depends on
which shell it is transferring from / to. The atom of every element
releases X-rays with unique amounts of energy, identifying it.
The output of an EDX analysis is an EDX spectrum, which is just a
plot of how frequently an X-ray is received for each energy level. The
higher a peak in a spectrum, the more concentrated the element is in
the specimen.
THE SUPPORT PC
includes a PC, a LCD monitor and a software-controlled Switch Box. It
is required for the EDX functionality and can also hold some other
software utilities.
FIGURE 9-13 INSPECT STANDARD LAYOUT SCHEME
HIGH VACUUM EDX ANALYSIS
HiVac operation gives the most accurate X-ray results, but the sample
must be electrically conducting.
FIGURE 9-14 X-RAY IMAGING IN HIVAC MODE