-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dear B. Vijay,
for single-wavelength (as opposed to Laue) X-ray crystallographic data collection it is in general helpful to mount your crystal in an arbitrary orientation. If you happen to mount it such that a symmetry axis is parallel to the rotation axis, you may not be able to collect fully complete data. Indexing routines figure out the orientation of your crystal. After integrating all reflections, the orientation is refined (depending on the integration program you use). For anomalous data you may want to collect in inverse beam mode which makes sure you collect Bijvoet pairs close in time and thus reduce the effect of radiation damage. As drawback you risk possible systematic errors in the Bijvoet pairs, but I am not sure this is a major drawback for MX crystals. I recomend you take a look a Zbigniew Dauter's article "Data-collection strategies", Acta Cryst D55 (1999) p. 1703-1717 doi:10.1107/S0907444999008367 Best, Tim On 10/27/2012 07:58 AM, Vijayakumar.B wrote: > Dear CCP4BB users, > > > I have some basic questions in the data collection. Please give me > some ideas to get clear in this part. > > > 1) Why orientation of the crystal is importance? > > > 2) If we mounted the crystal in arbitrary, what it leads? > > > 3) How to find out crystal misseting angels in the data > collection if we mounted arbitrary? > > > 4) What should we make clear before collecting anomalous signal > data ? > > > Thanks in advance. > > > With regards > > B. Vijay > > - -- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iD8DBQFQjmJQUxlJ7aRr7hoRAmZnAJ9HwuG1ITVs9qKlhUL0kz/yDP+H+ACggEPl VajYAhsCbbDzbPhYmsvArxU= =zkqj -----END PGP SIGNATURE-----
