Dear Ken
There's an experiment called "gradshim1d1h". Run the experiment, process
the fid with "fmc". You should get a profile something like a "soft
rectangle" (each probe will have a unique profile). It is best to use a
sample with a strong 1H signal, something like a water suppression test
sample, or a doped 2 Hz water sample.
Kind regards,
Craig.
On Thu, 4 Jan 2024 at 21:11, DrSpin <rajanp_at_uw.edu> wrote:
> As to generating gradient echo profile as a diagnostic tool for dirt in
> probe, I don't have much experience with that. But I want to add that if
> there is an insert glass breakage, it shows up noticeably in the profile,
> more so with 1H profile that can be generated as a 3D image.
>
> Topshim can be run with the option "topshim 3d map" and it will retain
> the datasets from which we can examine the before and after field maps (it
> usually deletes the datasets after shimming is done).
>
> Rajan
>
> On Thu, Jan 4, 2024 at 11:03 AM DrSpin <rajanp_at_uw.edu> wrote:
>
>> Happy new year, all !
>>
>> Ken, prior to the days of Topshim and gradient probes, it used to be my
>> practice to run a monthly round robin of all existing instruments that
>> included the touch up of shims and saving them in a standard file called
>> 'stdbbo', for instance. If you do not have a particularly bad i.e.
>> drifting magnet, then the higher order shims used to stay pretty well in
>> the global minimum. So, I used to do hand shimming with the method nicely
>> summarized by Woody Conover (RIP, Woody !) upto the XZ2 and YZ2
>> combination for transverse and upto Z4 for axial (Z5 should be pretty small
>> if there are no serious edge effects) and then let the system run a Simplex
>> optimization for the entire shim set before I head home. Outermost, it
>> used to take about 8 hours for 20+ shims. Both for hand shimming and
>> overnight simplex, I use Lineshape standard 1% CHCl3 in Acetone-d6.
>>
>> With the advent of Topshim, I simply run a 1H 3D Topshim on either
>> Sucrose standard in 90:10 H2O:D2O or an in-house decoy sample that we have
>> made in bulk which is Aspirin dissolved in H2O:D2O. This is the sample we
>> keep in all magnets when no user sample is in the magnet. So, that's my
>> droplet of wisdom added to your Cornucopia of tricks.
>>
>> Best Regards
>> Rajan
>>
>>
>>
>>
>>
>>
>> On Thu, Jan 4, 2024 at 10:45 AM Sham, Shing <ssham_at_luc.edu> wrote:
>>
>>> Ken,
>>> There is a parameter set called topshim1d2h, or something like that.
>>> That should help you to see the z-axis shim profile immediately.
>>> Also, a small shoulder peak should attach to the main peak at the
>>> baseline that you could not shim off with z4 if the probe is dirty or
>>> something stuck there.
>>>
>>> Hope this helps and good luck.
>>>
>>> Simon
>>>
>>> ------------------------------
>>> *From:* main_at_ammrl.groups.io <main_at_ammrl.groups.io> on behalf of
>>> Kenneth Sharp-Knott via groups.io
>>> <kknott=vt.edu_at_groups.io>
>>> *Sent:* Thursday, January 4, 2024 12:09 PM
>>> *To:* ammrl_at_groups.io <ammrl_at_groups.io>
>>> *Subject:* [AMMRL] Shimming issues
>>>
>>> I seem to waste a lot of time getting my shims in order when they
>>> suddenly go out of order.... Curious if anyone has a more procedural
>>> method correcting their system shims. I am primarily talking about Bruker
>>> instruments of which I have older ones which are persnickety...
>>>
>>> I am also interested in a good way to evaluate if the probe is dirty.
>>> I'm dealing with Prodigy probes so I can't drop them easily. I have seen
>>> engineers determine this by looking at the gradient profile I believe? How
>>> is this done?
>>>
>>> Best
>>>
>>> --
>>> Ken Sharp-Knott
>>> Manager of Analytical Services and the NMR Facility
>>> Department of Chemistry
>>> Virginia Tech
>>>
>>> (540)267-6502 (Cell)
>>> (540)231-0885 (Office)
>>>
>>>
>
>
> ____________________________________
> Rajan K Paranji, Ph.D. NMR Services Manager *Department of Chemistry* *Room
> 65, Bagley Hall* University of Washington Seattle, WA 98195 phone : 206
> 685 2581 fax: 206 685 8665 email: rajanp_at_uw.edu
> ____________________________________________________________________
>
>
>
>
>
>
>
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