Isn't the simplest answer that this is not really an Argand diagram with
real and imaginary axes, but simply a diagram showing the graphical addition
of the component phasors of the atom's scattering components? And aren't
real and imaginary relative terms anyway (in more ways than one, I guess!)?
Jacob
----- Original Message -----
From: "William Scott" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 13, 2010 12:48 PM
Subject: [ccp4bb] embarrassingly simple MAD phasing question
Hi Citizens:
Try not to laugh.
I have an embarrassingly simple MAD phasing question:
Why is it that F" in this picture isn't required to be vertical (purely
imaginary)?
http://www.doe-mbi.ucla.edu/~sawaya/tutorials/Phasing/phase.gif
(Similarly in the Harker diagram of the intersection of phase circles, one
sees this.)
I had a student ask me and I realized that there is this fundamental gap in
my understanding.
Many thanks in advance.
-- Bill
William G. Scott
Professor
Department of Chemistry and Biochemistry
and The Center for the Molecular Biology of RNA
228 Sinsheimer Laboratories
University of California at Santa Cruz
Santa Cruz, California 95064
USA
phone: +1-831-459-5367 (office)
+1-831-459-5292 (lab)
fax: +1-831-4593139 (fax)
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Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
Dallos Laboratory
F. Searle 1-240
2240 Campus Drive
Evanston IL 60208
lab: 847.491.2438
cel: 773.608.9185
email: [log in to unmask]
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