Hi Richard The only ones I'm aware of is this one: Acta Cryst. (1990). A46, 315-320, the one mentioned by Colin: Acta Cryst. (1991). B47, 960-968, and this review: Crystallography Reviews, (2003), 9, 229-277.
Cheers -- Ian > -----Original Message----- > From: owner-ccp...@jiscmail.ac.uk > [mailto:owner-ccp...@jiscmail.ac.uk] On Behalf Of Richard Gillilan > Sent: 27 November 2009 02:37 > To: Ian Tickle > Cc: CCP4BB@JISCMAIL.AC.UK > Subject: Re: [ccp4bb] decrease of background with distance? > > > David had developed an empirical theory to model the > air, solvent, > Compton & acoustic contributions and correct the > integrated data for > these, without background correction of course since > the optic DS > background was ultimately to be our data! > > ... > > Hi Ian, did David publish this theory somewhere? I'd love to > get a reference. > > > > > > > > I'm genuinely confused by this because I > thought the whole point of > modern focusing optics (or at least the > confocal mirror design) is to > focus the beam onto (or close to) the sample, > in which case > wouldn't the > photons diverge from the 'virtual source' > (actually a real > image of the > real source) at the crystal, instead of from > the real source? So then > Bragg spots (and therefore also the acoustic DS) should > diverge from the > position of this virtual source? > > Cheers > > -- Ian > > > > > This does seem confusing now. Here at CHESS, focus is either > at the collimator (just upstream of the sample), or, in the > case of capillaries, on the sample. In rare cases, on the > detector. True, the focal spot would be a virtual source > and, if the spot is reflected by an ideal crystal, that > wouldn't change anything. But it is a very well collimated > source even though it is slightly divergent (by a few mrad at > most) ... this is in contrast to background scatter where > photons are emitted in the whole q range (assuming it is > "that kind" of scatter). So maybe it is more accurate to say > Bragg reflections and background scatter are two rather > different kinds of sources located at the crystal. > > Pardon my ignorance, but how can lattice phonons be a > significant effect at low temperature? I presume the > correlated displacements you refer to must be phonon modes > frozen in place to create static disorder or something like > that ... or perhaps stuff is moving more than I think at 100 K. > > Richard > > > > > > > > > > Disclaimer This communication is confidential and may contain privileged information intended solely for the named addressee(s). It may not be used or disclosed except for the purpose for which it has been sent. If you are not the intended recipient you must not review, use, disclose, copy, distribute or take any action in reliance upon it. If you have received this communication in error, please notify Astex Therapeutics Ltd by emailing i.tic...@astex-therapeutics.com and destroy all copies of the message and any attached documents. Astex Therapeutics Ltd monitors, controls and protects all its messaging traffic in compliance with its corporate email policy. The Company accepts no liability or responsibility for any onward transmission or use of emails and attachments having left the Astex Therapeutics domain. Unless expressly stated, opinions in this message are those of the individual sender and not of Astex Therapeutics Ltd. The recipient should check this email and any attachments for the presence of computer viruses. Astex Therapeutics Ltd accepts no liability for damage caused by any virus transmitted by this email. E-mail is susceptible to data corruption, interception, unauthorized amendment, and tampering, Astex Therapeutics Ltd only send and receive e-mails on the basis that the Company is not liable for any such alteration or any consequences thereof. Astex Therapeutics Ltd., Registered in England at 436 Cambridge Science Park, Cambridge CB4 0QA under number 3751674
