Hi Group;
We have a Bruker Broad Band 7mm cpmas probe and have been searching for
the source of a background signal while pulsing C13. The signal is present
whether or not a sample is in the probe, but does disappear when the probe
is removed from the magnet, thus it 'acts' like a real resonance. The signal
also tracks the transmitter offset or a change in the field. We have
removed the stator assembly and even built a stand alone coil made from
silver wire to no avail. The only thing that has diminished the signal is
to remove the outer aluminum shell or to use the antiring or "DEPTH" (D. G.
Cory and W. M. Ritchey, JMR., 80, 128 ( 1988)) pulses. We tuned the probe to
observe Al but observed a similar but smaller signal. Has anyone else
seen this and/or know the cause of this spurious signal. Has anyone heard of
"magneto acoustic resonance"?
Tom
Tom Nakashima
Chemistry Department
University of Alberta
Edmonton Alberta
Canada T6G 2G2
e-mail address:
vnmr1_at_ultranmr.chem.ualberta.ca
Received on Tue Feb 15 2000 - 19:44:27 MST