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I would like to run some solid state 14N NMR spectra, but I have never run experiment on integer spins in the solid state. Can somebody give some advise, for example what experiment should I start with, are there some experiments to be avoided, some references that couls help me for the beginning? Thanks! Anne |
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Anne, If you can provide some insight as to your motivation for wanting to run 14N it would be helpful in providing you with some good background information. For example, what kind of chemical system(s), interest in structure, dynamics, spin physics and so on. Joseph |
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Nothing wrong with CPMAS. I just thought it was unnecessary. NH4Cl is cubic IIRC so no quadrupole coupling and I guess no CSA. It's also possible that the ammoniun has some rotational freedom even in the solid state which should reduce any dipolar coupling. |
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Thanks a lot! I think I will start with NH4Cl ! Unfortunately I have got only CPMAS probes, what is the problem with those probes? |
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I've run many solid state 14N spectra (I'm actually more interested in NQR than NMR). Just using a normal probe (not CPMAS) there are no real problems except for the linewidths. Obviously the main problem is the quadrupole coupling so the more symmetric the environment at the nitrogen site the better. Ammonium ions come out real sharp (well for solid state spectra). Strangely T1 is not normally a problem. 14N T1's are shortish the longest I have ever found is 10 s normally it is in the millisecond to second range. Dipolar broadening does not normally seem to be a problem presumably because of the small magnetogyric ratio of 14N and I believe that half-integral and integral spins do not couple too well. Whether any useful information can be extracted from 14N NMR spectra is another matter. |
