Area Detectors vs 2 Difractometers for Small-Medium Size Molecules (fwd)

Allen D Hunter adhunter at cc.ysu.edu
Tue Oct 4 14:28:37 EST 1994



---------- Forwarded message ----------
Date: Thu, 29 Sep 1994 16:27:16 -0400 (EDT)
From: Allen D Hunter <adhunter at cc.ysu.edu>
Newgroups: sci.techniques.xtallography
Subject: Area Detectors vs 2 Difractometers for Small-Medium Size Molecules

 
We have funding to buy a new X-ray difractometer system.  We will do much
of the crystallography ourselves as well as using the instruments in
student research and advanced lab/structure courses.  Extra diffractometer
time will be made available to people at other schools (particularly
undergrad schools) when we go on line.  Our work will mostly be on
traditional organometallics, organics, and solid-state oxides etc.  We
have also prepared some macromolecules and are considering hiring a
macromolecular/protein crystallographer.  Since the various manufacturers
have realized that we now have cash in hand, their prices on various
systems has droped and it now looks like we can aford a substantially more
capable system than we initially expected.  The most promising proposals
from them boil down to two categories.  A sealed tube difractometer (new)
with a demo model of an area detector (multi-wire proportional) and all 
of the
 software to do data reduction and analysis (including their protein
software) or two separate difractometers.  It seems that the main
advantage of the area detector system is that it will speed up data
collection and allow us to do powder and oriented fiber sample (all for
Cu) in our labs while the option of a second difractometer would allow us
to leave one on Cu and one on Mo at all times (i.e. less changing of
tubes, alligning, etc.) but we would be out the powder and fiber
capabilities. 
I would appreciate any thoughts on the relative merrits of the two
approaches.  As a beginning crystallographer, I also would like
opinions/info on several other topics:
	(1) Has anybody had experience with using a multiwire 
proportional area detector on small molecules, especially with Mo 
radiation?
	(2)  How would people judge the relative reliability of the 
Nonius, Rigaku/MSC, and Siemens systems?
	(3)  What are people's thoughts on buying a workstation vs a PC 
driven system.  Is the extra cost of an SGI or other UNIX system worthwhile?
	(4) Which of the commercial software packages are easiest for
students to pick up? What are the trade-offs
 

I realize that these thoughts are quite open ended but I would appreciate
any help I can get. 


Thanks for your help. 

 Allen Hunter
Department of Chemistry
Youngstown State University






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