On Wednesday 22 April 2009 09:23:19 Jacob Keller wrote:
> Hello All,
>
> What is the reason that x-ray fluorescence is neglected in our experiments?
> Obviously it is measureable, as in EXAFS experiments to determine anomalous
> edges,
> but should it not play a role in the intensities as well? What am I missing?
Fluorescence is directly proportional to f", so in one sense we do account
for it in any calculation that includes the anomalous scattering terms.
If you were thinking of direct contribution of the fluorescent X-rays to the
measured Bragg peak - that is negligible. Those photons do not retain the
momentum vector of the original incident photon, and are emitted in all
directions. I.e., they contribute even less to the diffraction image than
air-scatter from the direct beam or from the diffracted beam.
Ethan
>
> Jacob
>
> *******************************************
> Jacob Pearson Keller
> Northwestern University
> Medical Scientist Training Program
> Dallos Laboratory
> F. Searle 1-240
> 2240 Campus Drive
> Evanston IL 60208
> lab: 847.491.2438
> cel: 773.608.9185
> email: j-kell...@northwestern.edu
> *******************************************
>
> ----- Original Message -----
> From: rui
> To: CCP4BB@JISCMAIL.AC.UK
> Sent: Wednesday, April 22, 2009 11:06 AM
> Subject: [ccp4bb] microbatch vs hanging drop
>
>
> Hi,
>
>
> I have a question about the method for crystallization. With traditional
> hanging drop(24 wells), one slide can also hold for multiple drops but it
> requires the buffer quite a lot, > 600uL? Microbatch can save buffers,only
> 100uL is required, and also can hold up to three samples in the sitting
> well. Other than saving the buffer, what's the advantage of microbatch? Which
> method will be easier to get crystals or no big difference? Thanks for
> sharing.
>
>
> R
--
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742
