0
|
Hi, We have a Bruker MAS probe (4mm, late 90s vintage, widebore) that reports a spin speed twice what it is actually doing. We've cleaned and remarked the rotor but it hasn't helped. Any suggestions on how to fix this would be appreciated Kate |
|
0
|
Hi, We had such a problem a few years ago on an old spectrometer, the measured spinning speed was random and erratic, but not systematically twice the correct value... we solved the problem using a new shielded cable provided by Bruker, there was a problem of parasite frequency somewhere. |
|
0
|
Hi, maybe it helps to clean the spinning speed detector itself. Just below the MAS stator from where the light goes onto the rotor. Johanna |
|
0
|
Please note, a very similar question was posted and answered here: http://qa.nmrwiki.org/question/277/about-sideband-in-solid-state-nmr |
|
0
|
Thanks for the suggestions - it does seem as though it was the rotor (although we had cleaned it and remarked it). |
|
0
|
If the rotor is clean and marked correctly. And you have cleaned the spot on the probe where the optical fiber reads the rotor, you may need to polish the end of the optical fibers or replace the optical fiber. This could be a result of fracture in the light pipe or a rough surface on the optical fibers. Use the finest grit sand paper (~600 or 1200) and wash with Methanol to polish the ends. If the polish does not work try replacing the fibers. !!!!! Before you go pulling out the optical fiber or polishing the end, double check that all the connections are tight between the probe and console. Good Luck |
Is it only this one rotor or does it happen with each rotor that you put in? - Pascal Fricke (Oct 31 '13 at 03:22)