Multiple-Quantum Cross-Polarization and Two-Dimensional MQMAS NMR of Quadrupolar Nuclei

✍ Scribed by Sharon E Ashbrook; Stephen Wimperis

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 187 KB
• Volume: 147
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.2000.2174

✦ Synopsis

Cross-polarization from

1 H to the multiple-quantum coherences of a quadrupolar nucleus is used in combination with the twodimensional multiple-quantum magic angle spinning (MQMAS) NMR experiment in order to extract high-resolution CPMAS NMR spectra. The technique is demonstrated on 23 Na (S ‫؍‬ 3 2 ), 17 O, 27 Al (both S ‫؍‬ 5 2 ), and 45 Sc (S ‫؍‬ 7 2 ) nuclei, showing the applicability of multiple-quantum cross-polarization to systems with differing spin quantum number, gyromagnetic ratio, and relative nuclide abundance. The utility of this two-dimensional MAS NMR experiment for spectral editing and site-specific measurement of crosspolarization intensities is demonstrated. The possibility of direct cross-polarization to higher order multiple-quantum coherences is also considered and three-, five-, and seven-quantum cross-polarized 45 Sc MAS NMR spectra are presented.