George,
Occasional spikes could stem from discharges between coil and rotor. It
typically depends on what type of GAS you use for rotor spinning. If you use
N2 gas, it should disappear. Another possibility are dirty rotors, but in
that case, the arcs should disappear after overnight pulsing.
Another possibility is that your grounding between probe sleeve and Probe
body is worn and poor.
Good luck hunting!
Jochem
> From: main_at_ammrl.groups.io On Behalf Of Crull, George B via groups.io
> Sent: Tuesday, April 16, 2024 12:49 PM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] FID spikes while running CPMAS
I expect the spikes are coming from probe arcing.
I do occasional see them if the probe or rotor are dirty and are touching
briefly while spinning.
George Crull, PhD
Spectroscopist, Dept of Chemistry
230 N. Madison St, CB 275w, Iowa City, Iowa 52242
Office: 319-384-1315, Mobile: 215-262-9678
george-crull_at_uiowa.edu
http://www.uiowa.edu/
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Received on Tue Apr 16 2024 - 10:19:24 MST