Dear All!
... my suggestion is 'convection'. D2O is more viscous then Acetone.
To get a nice stable lock and shimming stuff, we lower the temperature to
290 K and all is nice again. Please keep an eye on the lock power.
DMSO and Benzene are also two nasty beasts - there you have to rise the
temperature.
If you go to -90 C then it can get also awful. This is a challenge to keep
all stable.
I made also some quite low stuff - with extra heated gas through the BST
shim system.
And was glad to come back again on room temperature.
Yours sincerely,
Ulrich Haunz
Am Dienstag, Januar 09, 2024 01:41 CET, schrieb "DrSpin" <rajanp_at_uw.edu>:
> Hi Ken
> I will thrown in this 'free of charge' wisdom, about the comment on the
> oscillating Lock vis-a-vis Bruker engineer's comment. To me it looks like
> the cause and effect are flipped in this case. Shims going out of whack
> can lead to your Lock dancing around and in this regard the Lock functions
> as a bellwether about how things are with B0 homogeneity, which is an
> expected role played by the apparent Lock level among other things. I
> don't readily see how the oscillating lock level can be grouped within the
> 'causes of the issue' camp.
>
> Albeit in a different system, I have seen this oscillating lock level
> when I used to run very low temperature experiments on my older 500 system
> with RT probe (ca. -90C or so) and it used to be impossible to shim this in
> any meaningful way. Of course, the cause here is the shim stack's
> temperature continuously changing for as long as I want to run the
> experiment. (I successfully rigged a homemade setup to pump warmed up gas
> through the BST collar thereby stabilizing the shim stack temperature and
> the problem evaporated).
>
> So, the question to ponder over is if your shim stack temperature is stable
> or not in the Prodigy system. There is an automation script 'coiltemp'
> that can be run from the Topspin command line, with a time interval
> provided as an argument say : 'coiltemp 10' and it will record the shim
> coil temperature every 10 seconds and write it to an Ascii file in the
> user's home directory. The filename it records it is called 'coiltemp'.
> You can investigate it to see what is happening with your shim stack. There
> are three columns in the file, with the second being the time stamp and the
> third being the shim stack temperature.
>
> Best Regards
> Rajan
>
> On Mon, Jan 8, 2024 at 2:32 PM Walt Massefski <wwm_at_mit.edu> wrote:
>
> > Hi Ken,
> >
> > Following on Jeff’s last point, if you think the problem is
> > Prodigy-related, the Configuration page of the Prodigy display shows the
> > probe coil temperature (and lots of other things) - you might dial it up to
> > see if anything is cycling at about the time scale of your oscillation.
> > Best,
> > Walt
> > -------------------------------
> >
> > Walter Massefski, Ph.D.
> > Director
> > Department of Chemistry Instrumentation Facility
> > Massachusetts Institute of Technology
> > 77 Mass. Ave. Rm: 18-0090
> > Cambridge, MA 02139
> > T: (617) 253-2016
> > wwm_at_mit.edu
> >
> >
> >
--
=========================
Ulrich Haunz, Dipl.-Ing. (FH)
NMR-Spektroskopie
Raum L 710, L 807
NMR-Center M520, M521, M527
Postfach M 715
Fachbereich Chemie
Universitaet Konstanz
78457 Konstanz
Tel.: +49 (0)7531 88-4261 -> M521 Bruker Avance NEO 800
Tel.: +49 (0)7531 88-4422 -> L807 JEOL Lambda 400
Tel.: +49 (0)7531 88-4955 -> L710 Bruker AVIII HD 400
Tel.: +49 (0)7531 88-4956 -> M520a Bruker AVIII 600
Tel.: +49 (0)7531 88-4957 -> M527 Bruker AVIII 400 Automation
Tel.: +49 (0)7531 88-4958 -> M520 Bruker AVIII 400 WB
Tel.: +49 (0)170 9153213
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Received on Tue Jan 09 2024 - 00:06:02 MST