Resolution Limits - Resolved?

George DeTitta detitta at
Thu Sep 21 09:38:20 EST 1995

This may not be the explanation, but then again...

The closest distance from crystal to image plate on the R-Axis II is 54 mm
and the distance from the center of the plate (2Theta=0) to the
edge along the equator is 100 mm.  That makes the maximum value of 2 Theta
along the equator equal to about 30 degrees.  For copper radiation that
translates into a maximum resolution of 1.5A.  To achieve higher resolution
it's necessary to change wavelength or swing the IP off of the symmetrical
positioning.  I am guessing that the peak in the bell curve reflects the
popularity of the RAxis IP device more than the inherent resoluion (diffraction
limit) of the macromolecule.

GDT / HWI    (detitta at


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