And then there is “The Lonely Struggle of the Long-Distance Shimmer”…
http://rsc.anu.edu.au/*chris/shimmer.html
Best Regards,
Jürgen
_______________________________________________
Jürgen Schulte, Ph. D.
NMR Specialist
Binghamton University
SN Building, RM 1024
25 Murray Hill Road
Vestal, NY 13850
Ph.: 607-777-4405
Fax: 607-777-4478
schulte_at_binghamton.edu
http://nmr.binghamton.edu/Schulte.html
> From: main_at_ammrl.groups.io On Behalf Of Molinski, Tadeusz
> Sent: Wednesday, October 11, 2023 2:55 PM
> To: main_at_ammrl.groups.io
> Subject: [External Email] Re: [AMMRL] Shimming From (almost) scratch on Varian
Joe,
Yesterday, when we were analyzing NMR spectra, I kept dodging the technical
errors in those measured data (“for reasons I won’t go into”).
Here’s an NMR users guide that goes back to the 1990s on the subject of
‘NMR magnet shimming’: or the ‘Art’ of removing
inhomogeneities in the magnetic field within the region where the sample solution sits.
In a mathematical terms, the state of homogeneity is a chief when all magnetic field
vectors become uniform: pointing in the same direction (parallel) and the same magnitude.
It is an absolute requirement for a high quality NMR spectrum!
‘In the old days’, shimming had to be done manually - literally turning
some or all of about a dozen dials (so called axial shims, Z0, Z1, Z3, etc. and
transverse shims X, Y, X**2…. X**2-Y**2! )that alter the DC current to
‘shim coils’ - until the ‘signal’ (a deuterium resonance)
was maximized. On most modern instruments, shimming is done automatically, but
apparently even now in PacHall, an inattentive operator can screw it up. Worse,
the don’t even notice!
- Ted Molinski
On Oct 11, 2023, at 10:17 AM, Mark Swanson <mark94131_at_gmail.com <mailto:mark94131_at_gmail.com> > wrote:
Hi David,
I've often found this article to be helpful. They go through a manual procedure
starting on page 13.
Cheers,
Mark
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Received on Wed Oct 11 2023 - 12:32:25 MST