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P. Wobrauschek, C. Streli, E. Selin-Lindgren:
"Energy Dispersive, X-ray Fluorescence Analysis";
in: "Encyclopedia of Analytical Chemistry", issued by: R.A. Meyers; John Wiley & Sons, Ltd., United States, 2010, 1 - 17.

Energy-dispersive X-ray fluorescence (EDXRF) is an
analytical method for qualitative as well as quantitative
determination of elements in a sample, independent of
their chemical form. It is built on the fact that elements that
are irradiated with high-energetic X-rays have a certain
probability of emitting characteristic X-rays, the energies of
which are unique for each element. In the energy-dispersive
(ED) systems, the emitted X-rays are detected via their
energies. The use of the EDXRF technique has accelerated
since the 1960s as a result of the development of liquid
nitrogen cooled solid-state detectors, nuclear electronics,
and small computers. Nowadays compact light-weight
electrically cooled detectors are available, which, together
with air-cooled low-power X-ray tubes, are perfectly suited
for handheld spectrometers. EDXRF is multielemental
and nondestructive and can be applied to large as well as
small samples of different composition and character. If
conditions are optimized, minimum detection limits can
be below the nanogram absolute or micrograms per gram
concentration level for small laboratory instruments and
into the femtogram or nanograms per milliliter region
for more advanced instrumentation (total reflection X-ray
fluorescence (TXRF), synchrotron radiation).
EDXRF spectrometers exist at many degrees of sophistication,
ranging from advanced laboratory instruments
to small portable instruments for field observations. They
can be designed for analysis of bulk material or for scanning
and elemental mapping of small areas. The use of
X-ray optics like single or polycapillaries and curved
mirrors in Kirkpatrick-Baez geometry lead to X-ray spot
sizes of micrometers and below ideally suited for micro-
XRF. Mapping with high spatial resolution is thus possible
opening investigations down to cell dimension.
Typical applications for EDXRF are analysis of
agricultural material, medical samples, archaeological
and historical objects, painting and fine art objects, and
environmental samples such as soil, ores, water, and
aerosol particles.

http://dx.doi.org/10.1002/9780470027318.pub.2

http://publik.tuwien.ac.at/files/PubDat_187656.pdf