On Thu, Oct 14, 2010 at 04:28:26PM -0500, Jacob Keller wrote:
> I have always found this angle independence difficult. Why, if the anomalous scattering is truly angle-independent, don't we just put the detector at 90 or 180deg and solve the HA substructure by Patterson or direct methods using the pure anomalous scattering intensities? Or why don't we see pure "anomalous spots" at really high resolution? I think Bart Hazes' B-factor idea is right, perhaps, but I think the lack of pure anomalous intensities needs to be explained before understanding the angle-independence argument.
>
We don't do this because your crystal is angle dependent - it usually does not
have the required degree of order to scatter thus far, so the anomalous signal
drowns in the noise.
> JPK
--
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
phone: +49 (0)551 39 22149
GPG Key ID = A46BEE1A
|