Heteronuclear dipolar decoupling effects on multiple-quantum and satellite-transition magic-angle spinning NMR spectra.
We here report on the influence of heteronuclear dipolar decoupling on the (27)Al 3QMAS, 5QMAS, and the double-quantum filter-satellite-transition magic-angle spinning (DQF-STMAS) spectra of a strongly dipolar-coupled system, gibbsite. The requirements for heteronuclear dipolar decoupling increase with the order of coherence evolving in the indirect dimension of a two-dimensional (2D) experiment. The isotropic line width of the high-resolution 2D spectra, in samples like gibbsite, is composed of four parts: the distribution of isotropic shifts (delta(ISO), delta(QIS)), the homogeneous broadening related to the proton-proton flip-flop terms, the (27)Al-(27)Al homonulcear dipolar couplings, and the (1)H-(27)Al heteronuclear dipolar couplings. It is shown that, even in the case of gibbsite, where a strong proton-proton bath exists, the main resolution limiting factor in these experiments resides in the (1)H-(27)Al dipolar interaction.
Ganapathy
S
S
National Chemical Laboratory, Pune 411008, India.
Delevoye
L
L
Amoureux
J P
JP
Madhu
P K
PK
D000535:Aluminum / Q000737:chemistry; D000536:Aluminum Hydroxide / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D008280:Magnetics; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011522:Protons; D011789:Quantum Theory; D012015:Reference Standards; D012680:Sensitivity and Specificity
D011522:Protons; D000536:Aluminum Hydroxide; D000535:Aluminum