[RASMB] Radial-dependent noise in Beckmann XL-I

[Leech, AP]

Hi All,

 From Anna's mention of different wavelengths I would infer it is seen
in absorption measurements rather than interference. However I agree
that running experiments away from 20C does seem to result in oil
deposition in odd places.

I would look at the intensity data from the scans for sample and
reference to see if there is a "drop" in light intensity, it could
be oil condensing somewhere along the light path anywhere from the
lamp to the photomultiplier tube, but the lamp assembly, any windows
and the monochromator are easiest to check.

Hope this helps,

Andrew


On 26/01/2012 13:43, Antje Voelkel wrote:
> Dear Anna,
>
> maybe you have a bit of oil dust condensed on the lens of the
> interference optics in the chamber. You can clean it with ethanol and a
> tissue. Eventually you have to repeat this two or three times. I check
> if its clean with the interference optics at low speed through an empty
> rotor hole. We sometimes have this problem if the measuring temperature
> differs from the room temperature. Most of the time heating is worse.
>
> Hope this helps!
> Best regards
> Antje
>
>
>
> Am 26/01/2012 13:33, schrieb anna vitlin:
>> Hello,
>> We have a Beckmann XL-I running a An-60 Ti rotor.
>> When running sedimentation velocity experiments at 4 deg. we have
>> noticed protein-independent, time-independent, radial-dependent noise,
>> consistently between 6.2 and 6.4 Radius.
>> This phenomenon occurs using different cell assemblies, different
>> wavelengths and different velocities but does not occur at 20 deg.
>> Has anyone detected behavior like this and how do we troubleshoot it?
>> Should we call for service?
>> Thank you
>> Anna Vitlin
>> Tel-Aviv university
>>
>>
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>
> --
> Antje Voelkel
> Max Planck Institute of Colloids and Interfaces
> Am Muehlenberg 1
> D-14476 Potsdam
> +49(0)331 567 9528/9531
>
>
>
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Dr Andrew Leech                   *  Laboratory Head
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