Re: [ccp4bb] Is anomalous signal a different wavelength?

- Protein crystallography

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

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Subject: Protein Crystallizer- AstraZeneca
From: "Ek, Margareta E" Margareta {- dot -} E {- dot -} Ek {- at -} ASTRAZENECA {- dot -} COM
Date: 2007-05-31

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Subject: Re: Is anomalous signal a different wavelength?
From: Jon Wright wright {- at -} ESRF {- dot -} FR
Date: 2007-05-31

James,

At least for diffraction experiments; the photon scatters off of the
*crystal lattice*, not any individual electron, so you can conserve the
momentum of the photons and the macroscopic crystal without the crystal
recoiling too much.

Best,

Jon

Murray, James W wrote:
>
> Dear All,
>
> While we are talking about X-ray scattering, I have another question. If
> an X-ray is elastically scattered from an electron at an angle theta,
> its energy is the same is the incoming X-ray. However, the momentum is
> not the same, as it now has a component in a perpendicular direction
> (see fig below). As I don't believe that the conservation of momentum
> really is violated, what is the source of the discrepancy?
>
> Contrast this with most textbook descriptions of Compton scattering,
> where the X-ray loses energy and the electron gains kinetic energy.
>
> best wishes
>
> James
>
> X-ray --------> e-
>
>
>
>
>
> Dr. James Murray
> Biochemistry Building
> Department of Biological Sciences
> Imperial College London
> London, SW7 2AZ
> Tel: +44 (0)20 7594 5276
>
>
>

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Protein Crystallizer- AstraZeneca
From: "Ek, Margareta E" Margareta {- dot -} E {- dot -} Ek {- at -} ASTRAZENECA {- dot -} COM
Date: 2007-05-31

Next message:
Subject: Rfree into an existing mtz...
From: James Pauff pauffjm {- at -} YAHOO {- dot -} COM
Date: 2007-05-31