> Dear Ammrlers,
>
> We are presently working with 17-O (68 MHz) on a 500 MHz
> liquids instrument. We find that tuning the probe for this
> frequency causes a loss of the 2-D lock signal (77 MHz).
>
> My instinct is that 10 MHz is a resonable separation.
> Does anyone have experience of how close it is possible to
> go to 2-D without causing problems.
>
I never use a lock when I am recording oxygen-17 spectra. Just like
sample rotation the lock really is not necessary for 17O, since the lines
are very broad anyway (usually several hunderd Hertz).
I just turn off the sweep and shim on the shape of the FID. It is even
recommended to disconnect the lock cable completely from the probe to
avoid any interferences.
For other nuclei that are close to 2H try using a 2H-Pass-Filter in the
lock channel and/or a 2H-Stop-Filter in the Xnucleus channel.
Juergen Schulte
Department of Chemistry
SUNY Binghamton
Binghamton, NY 13902-6016