dear dr mabry,
i would look for a cracked quartz insert in the rf coil section of the
probe. first turn the probe upside down and see if any glass bits fall
out. then take a look down the probe bore and see if you can see any
cracks. if you can, take the probe cover off and look at the top where
the rf coils are. there are several guartz tubes and one may be damaged.
possibly it was damaged in shipment?
yours
chrarles amass
smith college
Stephanie Mabry wrote:
>
> We have a QE-300 with a Tecmag pulse programmer that is not scheduled to be
> replaced for another 2 1/2 years. (We have the money, but are waiting on the
> space to be constructed.) The 1H-13C probe is a reconditioned probe just
> bought in January.
>
> Over the past couple months, we have had a problem with very predominant
> spinning sidebands. Initial attempts at shimming them away didn't work, but
> at one point, I was able to reduce the first order sidebands to below 2%.
> This lasted two weeks and now we have very large first, second, third,
> etc. -order sidebands. Adjusting the non-spinning shims currently only
> reduces the sidebands to around 6-7%.
>
> Any ideas what is causing these spinning sidebands to return? I was
> wondering if the magnet bore could need cleaned. The lineshape looks good.
>
> Thanks for the suggestions.
>
> Stephanie Mabry
>
> --------------------------------------------
> Stephanie Mabry, Ph.D., Instrument Manager
> University of Maryland, Baltimore County
> Dept. of Chemistry and Biochemistry
> 1000 Hilltop Circle
> Baltimore, MD 21250
> office (410)455-1031
> fax (410)455-2608
> mabry_at_umbc.edu
Received on Tue Apr 23 2002 - 09:07:27 MST