Hi Emily,
Congrats on the helium recovery system! Any and all attempts to conserve the
resource is applauded! Based on what I have gleaned from the pic, You would
need to install a longer loop, ( at least 2-3 meters for heavy gauge piping),
maybe less so for a thinner gauge..(it's trial and error I'm afraid), between
the hard plumbing and the cryostat. I would have to think that what you are
seeing is a vibration problem being conducted to the magnet through the current
hookup. You have essentially made null and void, any isolation through the legs....
instead of the vibes coming from the floor, they are now coming through the ceiling...
Regards,
John E. Hahn
CAZ Enterprises, LLC
6320 Fly Rd. Ste 207
East Syracuse, NY 13057
Ph. 315-727-8192
http://www.Cazent.com
________________________________
> From: main_at_ammrl.groups.io on behalf of Emily Crull via groups.io
> Sent: Tuesday, April 1, 2025 13:00
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: [AMMRL] Issue with shims on Agilent DD2 400 MHz
Hi everyone,
I'm still working on familiarizing myself with VNMRJ 4, and our Agilent has
recently encountered what is presenting as a shim based issue.
Over our spring break (Mar 16th-22nd), we had the hook up for our incoming
He collection system installed (featured in the picture). Since that occurred,
we have been having noticeably broader peaks in the 1H NMR spectra and simply
running Z-gradient shims isn't fixing the issue. This is appearing even in the
Ethylbenzene standard we have. We're just seeing humps with no resolved coupling
at all.
Here's what I can say about the magnet itself:
1. Based on the coin level I put on top of the bore, it is level, so the
legs appear to be keeping up with the added weight from the install.
2. The magnet is from 2012.
3. We haven't seen a change in our Helium consumption. Our Nitrogen meter
only registers in 5% increments and it's drop rate didn't change at all either.
4. I believe I have updated the shim map using a house made D2O standard,
but the issue still persists. The last shim map was from 2020.
5. The default "Gradient shim" button in VNMRJ that appears next to the
AutoLock and AutoTune is not improving the peak shape.
6. Using the Autoshim drop down menu and selecting "Z-gradient and 4 non-spin
shims" was sometimes resolving the issue.
7. The issue is not limited to one account and is being observed on the
admin account as well.
Any feedback on other ways to troubleshoot the issue and/or resolve it would
be greatly appreciated. If any other information would be useful in diagnosing
the problem, let me know what it is and I'll try and find it.
Many thanks,
Emily Crull
Director of Chemistry Shared Instrumentation
emily.crull_at_mail.wvu.edu
West Virginia University
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Received on Tue Apr 01 2025 - 10:35:17 MST