We had a similar problem with 31P NMR on our 400 MHz - a randomly phased peak o
at 150.68 ppm, which is exactly 162.000000 MHz on our system. We confirmed it
was external RF by collecting a single scan with all pulse powers set to zero,
AQ = 30, and O1 a few Hz away from the spurious peak - this produced an FID
with a non-decaying sine wave.
On a tip from Bruker, we checked our grounding wires and found the SampleMail and
magnet grounding wires were loose. Tightening them lowered the spurious peak's
intensity by a factor of 6, and it’s often within the noise now.
Best,
Sameer
--
Sameer Al-Abdul-Wahid, Ph.D.
Manager, Nuclear Magnetic Resonance Centre<
http://nmr.uoguelph.ca/>
University of Guelph
519-824-4120 x58914 / s.wahid_at_uoguelph.ca
> >From: main_at_ammrl.groups.io on behalf of john_at_process-nmr.com
> Date: Thursday, December 4, 2025 at 11:14
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Tiny dispersive peak in 13C NMR.
Looks like an RF artifact (spike) to me. If you turn off all line-broadening
and zoom into the signal it is very narrow and not displaying "lineshape"
characteristics and the fact that the phasing is "anti" the rest of the
spectrum all points to an artifact.
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Received on Fri Dec 05 2025 - 06:35:56 MST