Efficient Double-Quantum Excitation in Rotational Resonance NMR

✍ Scribed by T Karlsson; M Edén; H Luthman; M.H Levitt

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 197 KB
• Volume: 145
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.2000.2080

✦ Synopsis

We present a new technique for double-quantum excitation in magic-angle-spinning solid-state NMR. The method involves (i) preparation of nonequilibrium longitudinal magnetization; (ii) mechanical excitation of zero-quantum coherence by spinning the sample at rotational resonance, and (iii) phase-coherent conversion of the zero-quantum coherence into double-quantum coherence by frequency-selective spin inversion. The double-quantum coherence is converted into observable magnetization by reversing the excitation process, followed by a /2 pulse. The method is technically simple, does not require strong RF fields, and is feasible at high spinning frequencies. In [ 13 C 2 , 15 N]-glycine, with an internuclear 13 C-13 C distance of 0.153 nm, we achieve a doublequantum filtering efficiency of Ӎ56%. In [11,20 -13 C 2 ]-all-E-retinal, with an internuclear 13 C-13 C distance of 0.296 nm, we obtain Ӎ45% double-quantum filtering efficiency.