Hi All,
We are observing some strange sidebands on proton spectra on one of our
Varian Inova-500s. The sidebands are at +/- 11Hz, not coherent with the
main peak and often larger than the carbon satellites on a single
transient. Needless to say, they make HSQC, etc a waste of time. After
quite a bit of investigation we are fairly sure that we can say they do
not come from floor vibration, helium can vibration, nitrogen can
vibration, gas-flow effects ("tromboning"), breakdown of inline filters,
synthesiser fault, fault on the pre-amp / receiver system, VT system,
gradient amplifier, or cryogen level meter. They are also not apparent
on any of our other systems which are close by. They are quite clean
(discrete frequency) and seem not to change in frequency over time.
Has anybody seen anything like this elsewhere, or have any other
suggestions for sources we could look for, because we're pretty much at
the head-scratching stage.
Thanks,
--
Alan.
Alan M Kenwright Phone +44-191-334-2095
Senior Research Officer (NMR)
Department of Chemistry
University of Durham
Durham DH1 3LE UK
Received on Fri Oct 31 2003 - 11:21:26 MST