Background Signal in Solid State 13C NMR Spectra of Soil Organic Matter (SOM)—Quantification and Minimization
✍ Scribed by Ronald J. Smernik; J.Malcolm Oades
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 112 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0926-2040
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✦ Synopsis
13 C background signal, obtained for an empty rotor, was shown by spin counting experiments to be equivalent to 1 mg of observable carbon for cross-polarization (CP) spectra and 69 mg of observable C for Bloch decay (BD) spectra. The BD background was mainly due to Kel-F in the stator, with minimal signal detected from the Kel-F end-caps. The CP background was attributed to non-Kel-F components of the stator, probe, or probe supports. The BD background signal was eliminated by using a modified dipolar dephasing pulse sequence in which the absence of 19 F decoupling (rather than the absence of 1 H decoupling) causes selective elimination of the Kel-F signal.