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![[Figure 2]](he2010fig2mag.jpg)
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Figure 2
Anomalous dispersion of f′′ of sulfur. To a good approximation, f′′ increases with the square of the wavelength until it reaches a maximum of 4.1 electron units (eu) at the K-absorption edge of sulfur at 5.02 Å. There is an overshoot of f′′ and a shift of the edge which depends on the chemical state of sulfur. The edge of sulfur in sulfides is at 5.018 Å or 2470 eV (black bar) and that of sulfates is at 5.00 Å or 2480 eV (grey bar). At the edge the dispersion of sulfate with fmax′′ ≃ 12 eu is stronger than that of sulfur in methionine or cystein with fmax′′ close to 7 eu. The crystal structure of crambin has been solved by using a wavelength of 1.5 Å, indicated by a short bar (Hendrickson & Teeter, 1981  ), whereas in more recent studies the MAD method was used at wavelengths close to the K-absorption edge of sulfur (Stuhrmann et al., 1997). |
![[Figure 2]](he2010fig2.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
