| Autor: |
Furó, István, Halle, Bertil, Wong, Tuck C. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 11/1/1988, Vol. 89 Issue 9, p5382, 16p |
| Abstrakt: |
The response, in the frequency domain, of half-integral spin I>1 nuclei in anisotropic systems to the quadrupolar echo (QE) pulse sequence (π/2)x-τ-(π/2)y is investigated, with particular emphasis on the effects of quadrupolar relaxation. Using a state multipole formalism, we derive the frequency spectra produced by one- or two-dimensional Fourier transformation. Powder samples as well as uniformly and partially oriented samples are considered. The 2D QE experiment produces, in the F1 dimension (Fourier transformation with respect to τ), spectra which provide information about the static quadrupole coupling even if only the central line in the QE spectrum (obtained by Fourier transformation of the induction signal after the echo) is detected. For partially oriented and (incompletely dephased) powder samples, the F1 spectra allow the motional spectral densities to be determined with little or no effect of the inhomogeneous quadrupole coupling, which severely complicates the analysis of conventional (single-pulse) and QE spectra. For completely dephased powder samples (large splittings), the last of the multiple spin echoes gives rise to a triplet QE spectrum (for any I≥3/2), the satellite decay in which yields a transverse relaxation rate. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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