Tungsten 183 on AM400
Nick E Burlinson (nick@unixg.ubc.ca)
Mon, 2 Feb 1998 15:27:14 -0800 (PST)
Dear Bumers,
We have been attempting to observe Tungsten W183(14% abundant,I=1/2) on an
AM400 at SF0=16.674 MHz with a 20mm probe locked on D2O in a 20mm tube
also containing 2M NaWO4 as the std.reference soln.
Literature Refs.suggest we should be able to see a signal in 16 to 32
scans with relaxation delays of 1 sec.?? We used a PW=50-80usec.
The probe appears to be tuned to the correct frequency but there seems to
be some confusion over the correct value of SY, the synthesiser freq. The
Bruker manual claims that SY is calc.internally from the formula (400.13 +
o1 - 16.674)/4 which if o1=0 should give an SY=95.864. However after an II
command SY = 95.064??? This might suggest why we see no W183 signal over a
sw= 10000 and a series of ns=200 accumulations over a range of +-O1=100000
in increments of 7000Hz. Is it possible we could be way off the correct
frequency if SY is off? If anyone has had to deal with this problem,
suggestions would be greatly appreciated.
Regards,
Nick Burlinson
----------------------------------------------------------------------------
Dr.Nick Burlinson
Chemistry Dept./NMR SERVICE LAB
Univ. of British Columbia
Vancouver B.C.
CANADA V6T 1Z1
tel 604-822-6956
fax -2847
email nick@unixg.ubc.ca