Vector Diagrams of Structure Factors

Vector representation of F in complex plane

Friedel's law

Vector representation of a single anomalous scatterer

Note that f^o and the real part of the anomalous scattering (f ') are colinear, and that f " is 90 degrees phase shifted. Show that the crucial point is the mixing of cos and sin terms and that the little blue arrow to the left does NOT represent a cos term as in normal cases but a sin term ! Hint : f = ( f^o+f '+ if ") × (cos(phi) + i sin(phi))

Anomalous scatterer in protein

Note that both magnitude of F (and thus, intensity) and phase of F are different for F and -F. Fp = structure factor of protein alone, Fa is real part (both f' and fo) of anomalous scatterer, Fa" is f".

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This World Wide Web site conceived and maintained by Bernhard Rupp (br@llnl.gov)
Last revised April 06, 1999 11:05
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