Hi Venky
I have seen profiles like this when the glass insert/coil support was cracked.
Clemens
On 8/14/2026 2:59 PM, Uddigiri, Venkateswara Reddy via groups.io wrote:
Hi Bert,
Thank you for your help.
Regarding your suggestions:
ā¢ Check whether all shims are set (not only Z shims) and post a screenshot of the "Shims" panel.
I have uploaded the shim profile screenshot.
ā¢ The shim cable may not be correctly connected to the shim power supply, or a
fuse at the back of the power supply may have blown. You did not specify the console type.
The system is a DD2, and I have uploaded an image of the console and setup.
ā¢ Please insert the DāO or Autotest sample, perform an autolock, then go
to "Tools ā Standard Calibration Exp. ā Setup Gradient Shimming" and record
the trial profiles. Type "ff dss" in the command line and post a screenshot.
I have attached the requested screenshots.
ā¢ The NMR probe may have moved (typically downward) relative to the
shim tube, which would be visible as a misalignment of the two PFG profiles.
The probe was recently repaired, and unfortunately the previous manager did
not mark its original position. I have tried several insertion depths, but
I still observe the same broad underlying pattern. Images collected at different
probe positions are attached.
ā¢ If you see dips in the profiles (especially the lower profile), there
may be dirt inside the probe. In that case, remove the probe and clean the
sample bore with cotton swabs and isopropyl alcohol.
Do you think it would be worthwhile to test the probe while empty to determine
whether any signal might be arising from contamination or dirt inside the probe?
I plan to clean the probe next and will report back with the results.
Thank you again for your assistance.
Best regards,
Venky
________________________________
> From: main_at_ammrl.groups.io on behalf of Spin-Doc via groups.io
> Sent: 14 August 2026 12:33
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Varian NMR lineshape/shimming issue ā shoulders and broad components on all peaks
Dear Venky,
could you please try and report back the following:
- check whether all shims are set (not maybe only Z shims?) - please post a
screenshot of the "Shims" panel
- specifically if X/Y shims aren't set but even if they do, please click the
"Read default shims" button on the Shims panel. Any major changes in (XY) shims?
- the shim cable may not be correctly connected to the shim power supply or
a fuse at the back of it may have blown - you didn't specify what kind of
NMR console exactly you have - Mercury, Inova, VNMRS, 400MR, hence I don't
know which shim power supply you may have.
- please insert the D2O or Autotest sample, Auto Lock it and go to "Tools -
Standard Calibration Exp. - Setup gradient shimming and record the "Trial
profiles" spectra. Type "ff dss" in the command line and post a screenshot.
Might be that the NMR probe got moved (typically downwards) relative to the
shim tube - this would be visible by a misalignment of the two PFG profiles.
If however you see dips in the profiles (especially the second, lower one)
it may be that there is dirt inside the probe. In this case, remove the probe
and clean the inside of the sample hole at the top with cotton swabs and
isopropyl alcohol.
Best regards
Bert
Am 14.08.2026 um 17:22 schrieb Uddigiri, Venkateswara Reddy via groups.io
Dear AMMRL community,
I am looking for some advice regarding a persistent line shape/shimming problem
on our Varian NMR instrument.
We first noticed that our proton spectra showed unusual broad components/shoulders
underneath otherwise sharp resonances. Initially, I suspected a sample-specific
issue, but the same behaviour is also present with an ethylbenzene in CDCl3 standard.
A few observations:
*
The shoulders/broad components appear on essentially every peak.
*
The main peaks themselves can still look relatively sharp, but there is a broad
underlying component or shoulder.
*
I cleaned the inside bore of the magnet and repeated the experiment, but the
problem remained.
*
I also recorded the ethylbenzene/CDCl3 standard without doing any additional
shimming, and when the spectrum is expanded, the same broadness/shoulder is visible.
*
The spectra shown were acquired with the sample not spinning (0 Hz), so this does
not appear to be caused simply by spinning instability.
*
The instrument locks normally, but the line shape remains poor.
I have attached image showing: ethylbenzene/CDCl3 standard spectrum.
At this point, I am wondering whether this could be related to higher-order or
transverse shims, sample positioning, the probe, or another hardware-related
line shape issue rather than a simple Z1/Z2 adjustment.
Has anyone seen this type of line shape on a Varian system, where every resonance
shows a similar shoulder or broad pedestal? I would appreciate any suggestions on
the best way to diagnose this systematically and which shim terms or hardware
components would be most useful to check first.
Thank you very much for your help.
Best regards,
Venky.
Magnetic resonance equipment, service, training & more
Selling & buying used NMR equipment (all vendors)
Dr. rer. nat. Bert Heise
Owner, Applications Scientist
Spin-Doc Bert Heise
Kiefernweg 13
58239 Schwerte
Germany
Mobile: +49 171 5135315
Email: bert.heise_at_spin-doc.net
Web: http://www.spin-doc.net
Representing:
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http://www.stelar.it)
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http://www.mestrelab.com)
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http://www.barthel-hf.de)
--
==========================
==========================
====================
Clemens Anklin Ph.D. Vice President
Bruker BioSpin NMR Applications & Training
15 Fortune Drive NEW Phone: 978-313-5NMR(5667)
Billerica MA 01821 bluesky: _at_canklin.bsky.social
web: http://www.bruker.com
e-mail: clemens.anklin_at_bruker.com
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Received on Sat Aug 15 2026 - 05:43:31 MST