Does vibrating an NMR sample produce the same benefits and artifacts as spinning an NMR sample? Are there "vibration sidebands" above the C13 satellites and is there a line thinning effect on the sample spectrum? Please list any references that you may have read or seen.

Thank You


When you spin a sample you make sure that orientation effects are averaged faster than the relaxation time. This holds true if you spin a sample at 8 s^-1 and H1 relaxes at 1 s^-1. Now, wobbling (aka shaking) will keep orientation of the molecules for the most part (unless it creates spinning motion in the solution). It will change several %, but the general direction will be the same. So, no, shaking will not do the molecule averaging like spinning does.

Btw, why do we spin samples. I mean, if the tube is half decent and you spend 5 minutes on shimming you get about as good of a result. All spinning does is hiding poor XY shims by averaging them.

  • $\begingroup$ Possibly worth noting that with a good modern NMR machine we rarely spin samples these days. The combination of better probes and better NMR tubes makes the practice often unnecessary $\endgroup$ – NotEvans. Jul 15 '16 at 16:11
  • $\begingroup$ This is true but none of our spectrometers except a 600 cold probed Agilent vnmrs are modern. We never spin that one. I only asked the question because when calibrating (FID shimming) using a D2O standard there appeared a harmonic oscillation in the upper barrel of one of our Mercury NMR's and the lineshape instantly became much thinner than I have ever seen before and the FID decayed like it was an CDCl3/acetone standard sample. I never was able to force the vibrations to occur again and it has haunted me since. $\endgroup$ – 3dalliance Jul 15 '16 at 20:05
  • $\begingroup$ Also when I observed the line thinning during the vibration event I was fairly certain that it was not a wobbling vibration but rather and up-down oscillation in the z-axis (vertical for NMR magnets) because of the tolerances of the spinners. One might expect homogenization effects from poor Z shims also. $\endgroup$ – 3dalliance Jul 20 '16 at 17:34
  • $\begingroup$ sixtytrees; =)> Yes many researchers here at UF also do not spin to protect the probe and sample which if it's a natural products distillation could be worth many-many $K. This event that I observed with my instruments and my own two eyes still haunts me. Care to try it on one of your machines whereby you induce a vibration in the z-axis ONLY and observe the results? Anyone??? $\endgroup$ – 3dalliance Dec 23 '16 at 16:06
  • $\begingroup$ PS: I am Robert Harker - Engineer - rharker@ufl.edu AKA 3dalliance here and other places. $\endgroup$ – 3dalliance Dec 23 '16 at 16:24

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