Hello everyone!
It’s been a while since I contact the list with technical questions. Hope someone can help me with this one...
I am trying to record 11B-decoupled 1H spectra (that is, 1H-{11B} spectra). On the Bruker AVANCE there is a PROB11DEC parameter set which uses an ZGIG pulse sequence, so I calibrated the 11B pulses (the CPD pulses used for the WALATZ-16 are calculated from the 90 deg. 11B hard pulse), and gave it a go. If I set the number of scans to 1 I get great looking data. If I use more than 1 scan, I start getting weird results. All the successive 1H FIDs apear as if the phase was shifting from one to the other, and I get funny looking spectra (as if they where partially coupled). Funny thing is that if I just repeat the 1 scan experiment successively, I don’t see this problem.
I don’t know why, but I believe that it has to do with the (non-random) phase of the CPD sequence. Anyone has done this on a modern Bruker system?
More info: The sample is NaBH4 in D2O (yep, it has stopped fizzing...). I’m using a 70 us pulse for the CPD program, and the power was calculated from the 11B 90 deg. pulse (9.7 us at 50 Watts...).
Thanks in advance!
Guillermo
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Guillermo Moyna, Ph.D.
Profesor Agregado y Director
Departamento de Química del Litoral
Universidad de la República
Ruta 3 Km 363, Paysandú 60000
Tel: ++598-4722-7950 interno 131
E-mail: gmoyna_at_fq.edu.uy
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Received on Sat Aug 16 2014 - 12:56:59 MST