Thanks to Richard Shoemaker, Donna Baldisseri, David Redwine, Huaping Mo, Matthias Findeisen, and Bob Berno for answering my query. I got it working for my SiH and my quantitative spectrum with inverse gated decoupling (zgig) is much improved now. The two biggest changes thanks to the suggestions made were to use bi_waltz_16_32pl instead of the biwaltz_65_256 I had mentioned and to actually set my proton frequency (o2p) closer to resonance. It had been set at 6.5 ppm, and this peak is typically at 4.7 ppm in a proton NMR spectrum. When you get used to thinking on the Si-29 scale from +20 to -120 ppm, 1.8 ppm doesn't seem like a big deal.
Using bi_waltz_16_32pl, we did have 90 us 90o pulses for the WALTZ portion and 45 us 90o pulses for the CW portion, so I didn't have any problems in the prosol table.
I will note that shifting the resonance didn't really affect the decoupling sidebands for the WALTZ-n only sequences, and I still seemed to have more decoupling spikes in GARP decoupling than WALTZ decoupling even after making that one change. The bilevel decoupling definitely removed my initial offending decoupling sidebands. There are some new ones but are much smaller and not in potential key positions for other peaks I am trying to assign.
If I just changed the sequence but not the resonance frequency, these decoupling spikes were removed but spikes close to the actual peak showed up. These were removed by shifting the proton to on-resonance. Shifting the silicon on or off-resonance didn't seem to make a difference.
--
James M. Gibson, PhD
Lead Analytical Scientist
Momentive Performance Materials
(518)233-3668
James.gibson_at_momentive.com
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Received on Fri Oct 31 2014 - 05:38:58 MST