Co-59 NMR -Reply
Paul Keifer (paul.keifer@nmr.varian.com)
Fri, 16 Apr 1999 19:41:59 -0700
Letitia,
I have routinely used 0.05M solutions of K3[Co(CN)6] in D2O for
observing 59Co. The signal can be seen in one scan with adequate
sensitivity (probably > 30:1) on the 13C decoupler coils of 500 MHz
Indirect Detection-style probes. Observe frequency was 118.600 MHz
on a system with a 1H frequency of 499.849 MHz. I have measured the
T1 before, and I know it was not prohibitively long, but don't recall what
it was. The trick with this sample (which is also its virtue) is that if you
shim on the D2O lock, any temperature inhomogeneities within the sample
translate into 59Co linebroadenings (168 Hz per 1 degree C on a 500), so
make sure you have plenty of VT air flowing through the probe when
you start. Linewidths of 10-15 Hz or more are common; I don't think I
have ever seen it shim to less than 5 Hz (shimmed on D2O).
-Paul
*******************************
Paul A. Keifer, Ph.D.
Varian NMR Instruments
3120 Hansen Way D-298
Palo Alto, CA 94304-1030 USA
tel: (650)-424-6609
fax: (650)-852-9688
email: paul.keifer@nmr.varian.com
****************************p**
>>> Letitia Yao <letitia@nmr.chem.umn.edu> 04/16/99 11:33am >>>
Does anyone have experience detecting Co-59? We've been trying to
detect
this on our 300 MHz magnet (at 70.8MHz) with a 0.5M sample of
K3[CoIII(CN)6] and get absolutely no signal. Any suggestions for
acquisition times, recycle delays, number of scans, etc? Any help would
be appreciated.
----------------------
Letitia J. Yao | letitia@nmr.chem.umn.edu
NMR Laboratory | yao@chem.umn.edu
Department of Chemistry | (612) 625-8374 (office)
University of Minnesota | (612) 626-7541 (fax)