On Sat, 26 Jun 2010, Sudhir Kumar wrote:
> Hi ALL
> I don't know if I'm asking the right question:
> What are Remote, Inflection and peak values for X ray data collection?
> Sorry if question is wrong or under-status.
I wouldn't say it's under-status, and it's certainly a "correct" question.
The answers you got suggest the answer, that it pertains to
multi-wavelength anomalous diffraction (MAD) data collection. Also, it's
part of the basic teaching these days in macromolecular crystallography. I
know that sometimes it's hard to >get< that teaching.
I'm going to refer you to the lecture notes for an all-day lecture I give
once a year at our RapiData course, trying to help people brush up on
fundamentals:
http://www.px.nsls.bnl.gov/fundamentals_lecture/fundamentals_10_2_public.ppt
Of course these are the visuals, and there's talk that goes with it. Look
at graph in the upper left of image 150, which is labeled "Spectrum from
Phizackerly, Hendrickson, et al. Study of Lamprey Haemoglobin". That curve
is derived from the absorption of, in this case a Fe atom, as a function
of x-ray wavelength. Here it's in the range of 1.7 Angstroems, if you
can't see the decimal point. This curve is actually the imaginary
component of scattering from Fe. The "inflection" is the wavelength where
the curve rises VERY sharply, in this case about 1.74 Ang. The "peak" is
just that, the highest point at 1.73 Ang. Then the "remote" is chosen at
a shorter wavelength rather arbitrarily, in this case 1.5 Ang.
You still need to read more, but this should help you with that little
piece of MX jargon.
Watch for the announcement of RapiData, next December.
Bob
========================================================================
Robert M. Sweet E-Dress: [log in to unmask]
Group Leader, PXRR: Macromolecular ^ (that's L
Crystallography Research Resource at NSLS not 1)
http://px.nsls.bnl.gov/
Biology Dept
Brookhaven Nat'l Lab. Phones:
Upton, NY 11973 631 344 3401 (Office)
U.S.A. 631 344 2741 (Facsimile)
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