Yes indeed ! H2 is one product of H2O radiolysis by recombination of two H radicals. Whether or not the cleavage of iodine (quite efficient under X-rays) is a factor increasing H2 production, I don't know.
Philippe Dumas IBMC-CNRS, UPR9002 15, rue Rene Descartes 67084 Strasbourg cedex tel: +33 (0)3 88 41 70 02 [EMAIL PROTECTED] -----Message d'origine----- De : CCP4 bulletin board [mailto:[EMAIL PROTECTED] la part de Patrick Loll Envoye : Monday, March 03, 2008 6:00 PM A : CCP4BB@JISCMAIL.AC.UK Objet : [ccp4bb] radiation damage question 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 [EMAIL PROTECTED]
