X-ray Fluorescence
Introduction
X-ray fluorescence is a spectroscopic method
that is commonly used for solids in which secondary X-ray emission
is generated by excitation of a sample with X-rays. The X-rays eject inner-shell
electrons. Outer-shell electrons take their place and emit photons in the
process. The wavelength of the photons depends on the energy difference
between the outer-shell and inner-shell electron orbitals. The amount of
X-ray fluorescence is very sample dependent and quatitative analysis requires
calibration with standards
that are similar to the sample matrix.
Instrumentation
Solid samples are usually powdered and pressed into a wafer or fused in
a borate glass. The sample is then placed in the sample chamber of an XRF
spectrometer, and irradiated with a primary X-ray beam. The X-ray fluorescence
is recorded with either an X-ray detector after wavelength dispersion or
with an energy-dispersive detector.