Re: NMR near EPR

Robert D Scott (scott@iastate.edu)
Thu, 16 May 1996 23:27:14 CDT

> My supposition is that the stray field from the EPR doesn't make
>much inhomogeneity and the lock takes care of the field shift. No one
>reported having done the test to see if the NMR lines move or the lineshape
>changes when the NMR is unlocked and you run the EPR field up and down. We
>sometimes run unlocked for one reason or another. If anyone has or is
>willing to run such a test, I'd be very interested.
>
>Charlie

Couldn't resist Charlie's challenge...........
The center or our ER-200D magnet is 3.9M from the center of
our 400MHz/52 DRX. Running unlocked and increasing CF on the
ER-200 (X Band 9GHZ) from 40 to 4540 gauss did increase the
acetone resonance (10% CHCL3 in d6-acetone) by 0.93Hz.
Three measurements at each field, bounced the epr twice, 0.12Hz/point.
An intermediate value (2040 gauss) increased the acetone
resonance by .33Hz (one measurement).
Running locked, there was no difference (0Hz) between low
and high field.
This surprised me because the fields are orthogonal, but guess
that those vectors still add :).
Fortunately?? our epr isn't used very often :(, we're usually
locked, and its a really heavy piece of metal with nowhere else to go.

dave scott
iowa state university
515-294-4057