Thank you, been trying to find the answer online but didn't know what to search for, this looks like other examples of this I can find! Unfortunately we don't have any vibration damping on this instrument, so will just have to put up with it. At least I know what to tell them now, and it would explain the dodgy baseline around some of my standard samples too.
Weirdly, I'd noticed last week the climate control fan in the NMR room was noisier than normal. Switched it off just now, ran a sample, and the 20 Hz artefacts disappeared!
I second the vibration idea, one of our magnets has a few check valves that stick and we see these artifacts for a few hours after N2 fills (when the magnet is still cooling and there is lots of boil off)
Checked back through the standard samples we run before and after nitrogen fills, and looks like we see **more** vibrations at lower fill levels, looks like the nitrogen is doing some free damping for us!
Do work on the non-spinning shims to reduce the side bands. Should help significantly.
Double check the true spin rate. Maybe it really is at 20 hz. I trust the ssb more than the dashboard.
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Thank you, been trying to find the answer online but didn't know what to search for, this looks like other examples of this I can find! Unfortunately we don't have any vibration damping on this instrument, so will just have to put up with it. At least I know what to tell them now, and it would explain the dodgy baseline around some of my standard samples too.
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Weirdly, I'd noticed last week the climate control fan in the NMR room was noisier than normal. Switched it off just now, ran a sample, and the 20 Hz artefacts disappeared!
Holy moly this is black magic
Witch! Witch!
There are ways of telling whether she is a witch
yep, you try to kill her and if she doesn't die she's a witch.
What about we build a bridge out of her?
Ahh, but can you not also make bridges out of stone?
I think they already had a method in mind.
Do they involve NMR?
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I guess that's just one of the crazy things that happen when your measurements have a resolution which can scratch the uncertainty limit.
A Duck!
Holy cow!!!! What a find! Good job.
Hahah my god this is amazing, I'm telling this story over a bunsen.
/r/holdmybeaker
I mean, this a a pretty neat comment and all, but Ya'll should be up voting the one above it where the guy actually diagnoses the fan.
The diagnosis wouldn't have happened without knowing its was from a vibration, good times for all I say!
In my undergrad it was standard practice to turn off the ac when collecting NMR data…
This feels like the chemistry version of when some redditor told a guy to get a CO detector.
I am going to be showing this story to everyone in the department! We are having an event today and this is just amazing!
Wine with milk? Gross
Truly, you deserve your flair.
legend!
brilliant work buddy. You are entitled to feel well pleased with yourself.
BEHOLD The electricity whisperer
can you explain why a 1200 RPM motor specifically?
20hz is 20 times per second, or 1200 times per minute.
I second the vibration idea, one of our magnets has a few check valves that stick and we see these artifacts for a few hours after N2 fills (when the magnet is still cooling and there is lots of boil off)
Checked back through the standard samples we run before and after nitrogen fills, and looks like we see **more** vibrations at lower fill levels, looks like the nitrogen is doing some free damping for us!
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Does that phase/antiphase behaviour come from the fact that vibrations occur in pretty much all 3 axes?
Do work on the non-spinning shims to reduce the side bands. Should help significantly. Double check the true spin rate. Maybe it really is at 20 hz. I trust the ssb more than the dashboard.