Hi all,
I had an interesting experience, and wonder if others have seen
similar things.
I was collecting data from a crystal that contains an iodinated
macromolecule. After 2 days on a copper rotating anode, with the
crystal at 100 K, we experienced a detector problem, so I put the
crystal back into the dewar; it was diffracting nicely when I took it
off. For various reasons, I didn't get back to this crystal until
about 3 weeks later. When I put it back on the goniostat, the mother
liquor was milky white in appearance. There were no ice rings, but
alas the crystal only gave a few anemic spots around the beamstop.
Annealing didn't help, and I noticed that when I blocked the cold
stream, the milky white appearance didn't go away when the sample
thawed. I finally took the crystal off and looked at it under a
microscope, at which point I discovered that the milky white
appearance was due to the presence of bubbles in the mother liquor.
I seem to recall some talks on radiation damage in which people
mention the evolution of a gas (H2?).
So: Does this seem like a radiation damage phenomenon? And have
others seen this kind of delay in the manifestation of damage during
storage at liquid N2 temperatures?
Thanks,
Pat
------------------------------------------------------------------------
---------------
Patrick J. Loll, Ph. D. (215) 762-7706
Professor FAX:
(215) 762-4452
Department of Biochemistry & Molecular Biology
Director, Biochemistry Graduate Program
Drexel University College of Medicine
Room 10-102 New College Building
245 N. 15th St., Mailstop 497
Philadelphia, PA 19102-1192 USA
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