Page 238 - Essentials of physical chemistry

200 Essentials of Physical Chemistry

L
β
L
α

+Z

K
α
K
L
K
β
M
N
FIGURE 9.7 Bohr orbits K, L, M, and N showing x-ray Auger=fluorescence transitions.

FIGURE 9.8 Ron Jenkins (1932–2002) was an English scientist who lived in the United States. He wrote four
books on the analytical use of x-ray spectroscopy and published about 230 scientific papers and 11 book
chapters. He taught these topics at the Denver x-ray conference for some 30 years. He was the first recipient of
the Ron Jenkins Award given every two years by the organizers of the Denver x-ray conference and was
executive director of the International Center for Diffraction Data. He founded the X-ray Spectrometry—An
International Journal and he is the only person to have received both the Birks Award for x-ray spectrometry
and the Barrett Award for x-ray diffraction. (By permission from the International Center for Diffraction Data.)

The main reinforcement of the waves will occur for the n ¼ 1 angle, but the intensity of the second
order (n ¼ 2) angle can be large and often one must use filters or even a tandem second mono-
chromator to purify the first-order wavelength. In the case of x-rays, one can use a lattice of purified
LiF to disperse a source of x-rays [7]. In the highly oversimplified schematic of Figure 9.5, we see a
naive dispersal of the K a bands of x-rays from various elements. Actual electron microscopes with
XRF attachments are more complicated than Figure 9.5, but students need to know about the
basic principles based on the schematic in Figure 9.7 and greatly developed by Dr. Ron Jenkins
(Figure 9.8) and others. For instance, the schematic shows the principle of using the ratio of