Colleagues,
Our site has magnetic field perturbations, and we are evaluating different
solutions and vendors' assurances. We would be grateful to hear from
anyone who experiences similar perturbations and either just lives with it
or has tried a solution. The magnitude of our magnetic field fluctuations
are moderate, attributed to the DC currents in nearby train lines, causing
3-6 Hz shifts of an unlocked D2O line, in a nearby 500 MHz instrument.
Although the lock can keep the line on-resonance within 1 Hz, small
fluctuations about the base cause higher T1 striping in 2D spectra during
the hours when the trains are running.
Bruker asserts their 'SuperShield' magnet will not be affected. We have
also heard of wrapping a big Helmholz coil onto the magnet can, with
circuitry to correct external fluctuations, a method I think of as an
'external lock' circuit. Both vendors currently provide a digital lock
system which is allegedly better than the analog lock on the 500 MHz
mentioned above (a 1999 Varian UnityInova).
Can anyone relate any experience with any of these solutions of (a) a
digital lock, (b) a Bruker SuperShield magnet, or (c) the external field
correction coils?
(I'll post a summary if anyone requests)
-- Roger Kautz
-+=+-+=+-+=+-+=+-+=+-+=+-+=+-+=+-+=+=+-+=+-+=+-+=+-+=+-+=+-+=+
Roger Kautz Director, NMR Facility
Staff Scientist, Ph.D. tel 617 373-8211
Room 341 Mugar Life Science Bldg. fax 2855
Barnett Institute of Chemical and Biological Analysis
Northeastern University, 360 Huntington Ave, Boston MA 02115
Received on Mon Aug 22 2005 - 09:58:03 MST