X-ray fluorescence
(XRF) is the emission of characteristic “secondary” (or fluorescent) X-rays
from a material that has been excited by bombarding with high-energy X-rays or
gamma rays. Each element present in a sample emits its own unique fluorescent
x-ray energy spectrum. The emitted X-rays are collected by scintillations
counters, semiconductor (solid-state) detectors, charge coupled devices (CCD),
or other detectors. By simultaneously
measuring the fluorescent energy emitted by elements in the sample, XRF
analyzers can determine the elements present in the sample as each element has
a characteristic energy associated with its fluoresced X-rays. The relative quantity of elements can also be
determined by XRF. The technique is
widely used for elemental analysis and chemical analysis. It has found particular usein the
investigation of metals, glass, ceramics and building materials, geochemistry, mining,
forensic science and archaeology. XRF instrumentation is available in multiple configurations
including benchtop, portable, and hand-held models. XRF is a mature technique. Energy and
wavelength dispersive instrument are available. Instruments vary broadly
in price from approximately $20,000 up to $100,000.