[RASMB] Xl-I wavelength check question

[Virgil Schirf]

Greetings,

After the lamp,  low intensity outputs can be also attributed to dirty 
slit assemblies. The slit is 2 nm wide, so it doesn't take much oil or 
dirt to partially block this opening. Unfortunately, it is not generally 
a piece that can be maintained by a user. The foil the slit is cut into 
is glued onto the brass assembly and comes off easily with too much air 
pressure or other physical means. There are also two lenses in the 
assembly with one flat surface and one convex surface. They can be 
cleaned and reassembled so that the two convex surfaces meet to form an 
hourglass configuration. 

That being said, I would suggest that you have your service engineer 
clean or replace the slit if you have a clean lamp and low intensities. 
With the slit out, you can also check the surface of the underlying PMT 
to see if oil and dirt have built up on it.

Best regards,

Virgil

Leech, AP wrote:
> Hi everybody,
>
> Some systems, like our XL/I, have an extra window in the monochromator
> mounting socket, which helps save on lamp cleaning as it keeps the oil
> from "cracking" on the lamp surface. Our lamp intensity is quite low
> (~10000), whether this is affected by the extra window I don't know,
> but it doesn't go down much with use.
>
> It is worth checking this window from time to time - if your AUC has one
> you should have a special tool for extracting it (like a screwdriver
> with a round magnetic end).
>
> Best to all,
>
> Andrew
>
>
> Borries Demeler wrote:
>
>>
>> Hi Mark,
>> I should mention that we have to clean our lamps quite regularly, 
>> depending
>> on use perhaps every 2-3 weeks. The procedure is simple enough, it 
>> would be
>> worthwhile to have the service person teach you how to do it 
>> yourself. Sometimes other optical components also require cleaning, 
>> but the lamp
>> is usually the biggest culprit. Lamps do vary in intensity at 230 nm, 
>> most
>> I have come across range between 12-30 kcounts when cleaned. The UV 
>> intensity
>> is lost first, I guess dirt absorbs in the UV stronger than in the vis.
>>
>> Regards, -Borries
>>
>> _______________________________________________
>> RASMB mailing list
>> RASMB at rasmb.bbri.org
>> http://rasmb.bbri.org/cgi-bin/mailman/listinfo/rasmb
>

-- 

Virgil Schirf
Technical Director, Center for Macromolecular Interactions 
<http://cmmi.uthscsa.edu>
Department of Biochemistry, Rm 4.523U
The University of Texas Health Science Center
7703 Floyd Curl Dr.
San Antonio TX 78229-3900
Voice mail: 210 567-6590
Fax: 210 567-6595
Email: schirfv at biochem.uthscsa.edu <mailto:schirfv at biochem.uthscsa.edu>