[RASMB] Looking for help with the XL-A optics

Leech, AP andrew.leech at york.ac.uk
Mon Nov 28 03:05:06 PST 2011


Hello Osman,

I would also suspect the monochromator. Could it have been dropped or
accidentally damaged?

You may have done this already, but if not I would get someone to shine
a torch into the exit slit of the monochromator assembly, while you
push the actuator rod in the plug part (use a small plastic stick or
similar). You should be able to see the diffracted light coming through
and tell if there is any obstruction or if the actuator is not moving
smoothly. You can also see if the 400 nm filter is out of position.

I hope this is helpful,

Best regards,

Andrew

On 28/11/2011 00:41, Borries Demeler wrote:
> Dear Osman,
>
> I agree that the radial intensity variation is much greater than it should
> be. Also, the maximum emission intensity should be at 230 nm (+/- 1-2 nm).
>
> There are a couple of issues you should look at:
>
> 1. I would ask Beckman to send you a different monochromator that has been
> verified to work well in a different instrument. There may be a flaw with yours
> that causes the wrong wavelength to be set.
>
> 2. check other components in your optical path that may be obstructing
> the light path. They include the slit assembly. Be very careful when you
> clean the slit not to damage the film. Also clean the lens in the slit assembly.
>
> You should be able to get this to work by yourself, but let me know if you
> need help with instructions to clean the slit assembly. We can probably
> guide you over skype how to do this.
>
> Regards, -borries
>
>>
>> Dear RASMB subscribers,
>>
>> We recently noticed that the intensity scans taken by our XL-A show extreme
>> radial dependence. Furthermore, we discovered that our lamp was exhibiting
>> intensity peaks significantly shifted from their supposed wavelengths.
>>
>> Below are radial scans taken for empty holes and the counterbalance, and
>> also a wavelength-intensity scan taken at 6.5 cm:
>>
>> http://dl.dropbox.com/u/10119274/reanalyticalultracentrifugexla.zip
>>
>>
>> We tried cleaning the lamp and adjusting its alignment, but that did not
>> help.
>>
>> We are located in Saudi Arabia, and the local distributor does not have the
>> expertise to deal with an AUC. We contacted Beckman in Europe for help, but
>> they are being much slower in their response  than I had hoped.  Having the
>> AUC up and running again is of critical importance to the users at my
>> university (KAUST), since it is currently the only AUC in Saudi Arabia.
>> Therefore, the university's priority is to get it fixed in the shortest
>> time frame possible.
>>
>> If you or someone you know can resolve this problem, we'll be more than
>> happy to: a) pay a consulting fee (if the problem can be resolved by
>> remotely directing us); or b) pay for a round trip plane ticket, plus
>> lodging and a consulting fee, if the problem can only be resolved by
>> on-site service.
>>
>>
>> Please send your inquiries or suggestions directly to me at
>> osman.bakr at kaust.edu.sa
>>
>>
>>
>> Regards.
>>
>>
>> -Osman
>>
>>
>>
>>
>>
>>
>>
>> --
>> Osman Bakr
>> Assistant Professor
>> Materials Science and Engineering
>> King Abdullah University of Science and Technology (KAUST)
>> Building 3, Room # 3236
>> Thuwal 23955-6900
>> Saudi Arabia
>> Tel: +96628084439
>> http://www.kaust.edu.sa/academics/faculty/bakr.html<http://www.kaust.edu.sa/academics/faculty/bakr.html>
>>
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-- 
Dr Andrew Leech                   *  Laboratory Head
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