Hi

This is a powder diffraction pattern with a couple (or more) of small molecule/salt crystals attached to it (which give rise to the spots). The resolution of the rings isn't right for ice, so I'd guess they're due to your precipitant forming small crystals.

If you have a sample with large mosaicity (e.g. 360ยบ) you get rings like these. Powder crystallographers are paid to analyse them :-)

If you measure the resolution of each ring, you may be able to match them against known powder rings and find out what the chemical is. If you integrate around the circles you should be able to get values of I (or F...), and may be able to solve the structure; several groups are using area detectors for this now, rather than using linear powder diffractometers.

BTW, *please* don't post 1.5Mb files like this directly to the BB - this has caused some consternation in the past!

On 20 Feb 2011, at 13:46, Vandu Murugan wrote:

Dear All,
I mounted an aggregate with spikes on surface, that I saw in a well, and got a image attached with this. It has concentric rings.. What it could be? Any comments on it...?

thanks,
- Wandu
<image1.png>

Harry
--
Dr Harry Powell,
MRC Laboratory of Molecular Biology,
Hills Road,
Cambridge,
CB2 0QH

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