Hi MIke,
I began with topshim 2.0.0 and experienced all of those same things.
Including during 3D shims a long series of NS dependent tests that always
reverted to the 'default' and some kind of a B1 field
homogeneity experiment that never passed. I know that in the TS4
environment they are up to topshim 2.3.0 so that might show some
improvement. Those of us in TS3.6.5 are stuck on topshim 2.0.0 until the
next update....
I highly encourage you to provide this feedback to hotline_at_bruker.com as
I've found they are kind of blowing off these results in my case as a
'problem with older hardware'. Would be nice to have it reported on new
hardware.
Regardless, I think that topshim 2.0 is a work in progress as can be seen
by the growing version numbers. Still, the shims in my case usually end up
just fine, but with a lot of wasted attempts at failed convergence in
between.
Would like to hear others experiences with topshim 2.0
On Wed, Feb 15, 2023 at 4:31 PM AMMRL List <
ammrlrev_at_webserver2.chem.hawaii.edu> wrote:
> Dear Colleagues:
>
> We have recently had the good fortune of installing two new Neo systems; a
> 400 and a 500 both with SampleCase’s. As a result, I have said good-bye to
> TS2.1.8 and am getting familiar with TS4.1.4. With this jump in TopSpin
> comes a large jump and revamping of TopShim (1.2.2 à 2.2.0). Because
> TopShim looks quite different to me now in its reporting , Ive been
> watching it perform and report on both of these walk-up systems with some
> regularity.
>
> I have noticed on both of these new systems with RT probes (400 with a
> BBFO iProbe and 500 with BBFO SmartProbe) that TopShim’s behavior is
> usually as follows:
>
> - Iteration 1 is robust and results in a large improvement in
> homogeneity, usually ending up with a FWHM somewhere around 0.4-0.5 Hz
> - About 75-80% of the time, what follows is ~ 5 iterations where the
> FWHM oscillates between ~ 0.3 and 0.9 Hz, resulting in the message "slow
> convergence detected, shimming aborted. Using the best result as the final
> shim state". When I look at the maps, it appears that in the final 5-6
> iterations TopShim is trying to deal with the effects out at the edges and
> is unable to do so reliably.
> - I have noticed on both of these systems that z8 does not reliably
> converge but instead oscillates +/- 2000 units, on consecutive TopShim runs
> on the same sample. This is despite both of these systems having a BOSSIII
> shim system where ordmax=8 is supposed to be used according to
> documentation.
> - This behavior is independent of the TopShim observe nucleus (1H/2H).
>
>
> I am considering using the “fastfine” option on walk-up samples but what
> I’d really love to know is how I might tweak TopShim such that the above
> behavior is the exception rather than the rule. Is this a matter of using
> the zrange option to avoid the edges and thus shrink the region over which
> flattening is performed but where the hump is still tolerable?
>
> Id love to hear the group’s thoughts on this topic. I should be clear
> that the results we are obtaining from these two systems are absolutely
> fantastic! This email is just about me (possibly down a rabbit hole)
> wondering if with a deeper understanding even more can be gained.
>
> Thanks!
> Mike
>
>
>
>
> Michael D. Lumsden
> Nuclear Magnetic Resonance Research Resource
> Department of Chemistry, Dalhousie University
> 6274 Coburg Road
> P.O. Box 15000
> Halifax, Nova Scotia, Canada
> B3H 4R2
>
> Phone: 902-494-1635
> FAX: 902-494-1310
> Web: http://www.dal.ca/diff/nmr3.html
>
>
>
>
--
Ken Sharp-Knott
Manager of Analytical Services and the NMR Facility
Department of Chemistry
Virginia Tech
(540)267-6502 (Cell)
(540)231-0885 (Office)
Received on Wed Feb 15 2023 - 11:56:21 MST