CP MAS of quadrupolar S = 3 2 nuclei. Vega, A. J. Solid State Nuclear Magnetic Resonance, 1(1):17–32, February, 1992. Publisher: Academic Press
doi  abstract   bibtex   
The spin dynamics of Hartmann-Hahn cross-polarization from I = 1 2 to quadrupolar S = 3 2 nuclei is investigated. A density-matrix model applicable to cases where the quadrupole frequency νQ is much larger than the rf amplitude ν1S of the S spins, predicts the time development of the spin state of an isolated I, S spin pair in static situations and in three distinct cases of magic-angle-spinning speed νR. These cases are characterized as slow, intermediate, and fast, depending on the magnitude of the parameter α = ν1S2 νQνR relative to the intermediate value of 0.4. The model predictions are supported by numerical simulations. The polarization transfer from I to S is efficient in the limits of slow and fast sample spinning. When α ≪ 1, the Hartmann-Hahn condition is shifted over once or twice νR. When the spinning rate is intermediate, poor spin-locking of the quadrupolar spins prevents the accumulation of a cross-polarization signal and, in addition, depletes the spin-locked I magnetization. Experimental CP MAS data obtained in NaOH show that the concepts developed for isolated spin pairs are also applicable to cross-polarization in a strongly coupled multi-spin system. © 1992.
@article{Vega1992,
	title = {{CP} {MAS} of quadrupolar {S} = 3 2 nuclei},
	volume = {1},
	issn = {09262040},
	doi = {10.1016/0926-2040(92)90006-U},
	abstract = {The spin dynamics of Hartmann-Hahn cross-polarization from I = 1 2 to quadrupolar S = 3 2 nuclei is investigated. A density-matrix model applicable to cases where the quadrupole frequency νQ is much larger than the rf amplitude ν1S of the S spins, predicts the time development of the spin state of an isolated I, S spin pair in static situations and in three distinct cases of magic-angle-spinning speed νR. These cases are characterized as slow, intermediate, and fast, depending on the magnitude of the parameter α = ν1S2 νQνR relative to the intermediate value of 0.4. The model predictions are supported by numerical simulations. The polarization transfer from I to S is efficient in the limits of slow and fast sample spinning. When α ≪ 1, the Hartmann-Hahn condition is shifted over once or twice νR. When the spinning rate is intermediate, poor spin-locking of the quadrupolar spins prevents the accumulation of a cross-polarization signal and, in addition, depletes the spin-locked I magnetization. Experimental CP MAS data obtained in NaOH show that the concepts developed for isolated spin pairs are also applicable to cross-polarization in a strongly coupled multi-spin system. © 1992.},
	number = {1},
	urldate = {2020-03-30},
	journal = {Solid State Nuclear Magnetic Resonance},
	author = {Vega, Alexander J.},
	month = feb,
	year = {1992},
	note = {Publisher: Academic Press},
	keywords = {NMR spectroscopy, cross-polarization, notion, quadrupolar nuclei},
	pages = {17--32},
}

Downloads: 0