[RASMB] XL/I absorbance problem

Tom Laue tml at cisunix.unh.edu
Thu Jun 14 10:36:14 PDT 2007


Hi Andrew-
Sorry for the delay. It appears that the signal is saturated, even 
though it should not be. My suspicion is that either the reference 
signal conditioning or the A/D is the problem. It could be as simple as 
a dirty connection between the monochromator and the data acquisition 
board, or it could be more subtle (a bad channel on the A/D, 
incompatible firmware). Field service needs to look at it.
Best wishes,
Tom

Leech, AP wrote:
> Hello again,
>
> Many thanks to Virgil, John, Borries and Tom for such timely and
> informative replies.
>
> I have now attached two plots showing actual data: the first
> (IncidentIntensityComp.gif) shows the data from 00001.RN2 scan
> 280 nm velocity scan on an empty hole. The top trace is the
> incident and the bottom the intensity as seen through the empty
> hole. The second graph shows two incident (.RNx) plots. These
> were both at 280 nm; the top one from an old scan long before
> this problem arose and the bottom one from a recent scan. Note
> the different scales.
>
> I agree with Virgil that we may have a slit problem, but I think
> this is causing the broad dip in the intensity profile. The marked
> difference between the old and new incident light profiles makes
> me think the problem is with the lamp and/or reference detector.
>
> I've tried re-aligning the lamp (no difference) but I hadn't
> thought of swapping between machines. I'm not sure we can do this
> as the lamp housing is rather different on the old XL/A and I don't
> think it would fit.
>
> What I did wonder is whether it is permissible/advisable to try
> the XL/A monochromator in the XL/I? It would appear to fit, though
> it has less pins. But I don't know if this would do something
> nasty e.g. short out the laser power supply at the socket!
>
> Any further comments are appreciated - I will let you know the
> resolution (if any) of the problem.
>
> Best to all,
>
> Andrew
>
>
> ------------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> RASMB mailing list
> RASMB at rasmb.bbri.org
> http://rasmb.bbri.org/mailman/listinfo/rasmb
>   

-- 
Department of Biochemistry and Molecular Biology
University of New Hampshire
Durham, NH 03824-3544
Phone: 603-862-2459
FAX:   603-862-0031
E-mail: Tom.Laue at unh.edu
www.bitc.unh.edu
www.camis.unh.edu




More information about the RASMB mailing list