Dear all Would you have some tips on collecting datasets for S-SAD at a 'normal' beamline (tunable from 0.5-2.5 A)? How helpful/important is it to use mini kappa? Thanks.
Hi Mohamed,
I solved a structure at 1.5 A with Sulfur MAD. There were only 4 Sulfurs in
the sequence and the signal has very nice.
Pay attention S does not give high anomalous signal.
I suggest you collect a dataset at 7kev (around 2.0A) which is the
absorption edge of S. You must collect very high multiplicity around 30-40
times with low intensity beam not to burn the crystal. This at kappa 0 and
kappa 45. Then you could merge both datasets. I remember an important
thing, on the absorption edge we had to be careful on the harmonics and
make a nice setting on the beam to remove them. I suggest you do also a
collection at 14kev far away from absorption edge.
For my case only Autorickshaw found the Sulfurs and solve the problem of
phases.
Hope it helps,
Ivan
Sent with AquaMail for Android
http://www.aqua-mail.com
On 27 July 2015 7:17:18 pm mohamed noor
Dear all
Would you have some tips on collecting datasets for S-SAD at a 'normal' beamline (tunable from 0.5-2.5 A)? How helpful/important is it to use mini kappa?
Thanks.
---------- _______________________________________________ phenixbb mailing list [email protected] http://phenix-online.org/mailman/listinfo/phenixbb Unsubscribe: [email protected]
Hi Mohamed, On 7/28/2015 3:02 AM, Ivanov wrote:
I suggest you collect a dataset at 7kev (around 2.0A) which is the absorption edge of S. The absorption edge of sulfur is at 2.472 keV, which is 5.0155 A...
I suggest you ask the beamline scientist, which wavelength is suitable. Maybe the beamline can be tuned to 2.5 A, but the flux might become weak. Furthermore, absorption of X-rays in air (and the sample) is strong for wavelengths above 2.0 A. If kappa goniometer is available, I would use it. You can also collect data from several crystals, or several data sets at different spots from one crystal. I think it is difficult to give recommendations about the multiplicity you need. Collect data, then process and try to find the substructure during your beamtime. If you cannot find the substructure and solve the structure, collect more data and combine data sets. Hope that helps, Dorothee
On 27 July 2015 7:17:18 pm mohamed noor
wrote: Dear all
Would you have some tips on collecting datasets for S-SAD at a 'normal' beamline (tunable from 0.5-2.5 A)? How helpful/important is it to use mini kappa?
participants (3)
-
Dorothee Liebschner
-
Ivanov
-
mohamed noor