Hello Spinlanders,
What follows are responses to my query wrt 195Pt NMR observation.
________________________________________snip______________________________________
Well, I can honestly say that nobody has asked me about Pt-195 for six or seven years,
so I went back in the log and found a setup from 1994. Here are the parameters from our
AC-200 (the same VSP probe you use).
Tune 7852
Match 801
(C-3 on the BB preamp setup)
Our C-13 numbers on this probe are 7944/940
I didn't have a hexachloroplatinate sample, so I grabbed a 1000 ppm Pt standard from the
ICP lab. ( this is in 10% HCl and is probably PtCl4).
It took a few minutes with the reflection bridge to optimize to the numbers above, but I was
able to get the attached spectrum in 64 scans.
________________________________________snip______________________________________
About 195Pt-NMR measurements, here are experimental parameters.
In the attachment is a spectrum + parameters
of K2PtCl4 in D2O ( at -1614 ppm ) , good concentration, experiment
time is only 10 seconds.
(relative to Na2PtCl6 at 0 ppm).
We used:
BB-inverse probe
the pulseprogram is zg (zg-loop means it writes data to disk every
10,000 scans)
DigMod = analog
Basic 195Pt frequency is BF1=64.525135 MHz
spectral width 2218 ppm (= 142857 Hz, is about maximum value)
offset -2211 ppm (= -142720 Hz)
sfo1 = 64.3824143 MHz
Pulse 9 us (90 degree pulse is 11 us)
delay: D1= 0.02 sec.
Acquisition time: aq = 0.02 sec.
processing:
for this reference spectrum: Line broadening Lb = 35 Hz
Exponential multiplication: EM
For weak Pt samples we take 100,000 to 1,500,000 (18 hrs) scans and do
different processing:
Because there may be strong artifacts on the baseline,
also Linear Prediction- back ward is done, to recalculate about 50 data
points at the beginning of the FID.
It even gives crucial improvement of the spectrum.
Me-mod: LPbc
number of coefficients: ncoef = 200
Lpbin 0 (not used) or 130 (points used for Lin. Pred.)
time domain offset points TDOFF =50 (50 = normally best for weak
Pt-fid's)
use: Lb = 122 Hz or Lb = 240 Hz,
use EM before Fourier Transformation
________________________________________snip______________________________________
Its been awhile, but our AC-200 log book shows:
SF0 43.05 4 C 4.0 7863.2/836.9 on a 5mm VSP
90=7u SR -27620 for Na2PtCl6 set to 0
then later SR 22337 for K2PtCl4 in 1M NaCl set to -1628 ppm
________________________________________snip______________________________________
Kind regards,
Lawrence
Lawrence Byrnes,
NMR Laboratory Manager,
Numare Spectralab Incorporated
Research Director,
The Schoenenberg Institute of Molecular Spectroscopy
10 Summit Avenue, Building #6, P.O. Box 96,
Berkeley Heights, NJ, 07922-0096,
Voice: 908-665-0066
Fax: 908-464-4192
E-mail: numare_at_eclipse.net
Web: http://www.eclipse.net/~numare/
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Received on Thu May 30 2002 - 15:13:57 MST