Satellite transition spectroscopy

Physical background. MAS will narrow the inliomogeneously broadened satellite transitions to give a series of sharp sidebands whose intensity envelopes closely follow the static powder pattern so that the quadnipole interaction can be deduced. The work of Samoson [25] gave real impetus to satellite transition spectroscopy by showing that both the second-order quadnipolar linewidths and isotropic shifts are fiinctions of / and Some combinations of / and produce smaller second-order quadnipolar effects on the satellite lines than... 

Figure 5.4B) yielded a reliable quantitative estimate of the A1 occupancy of the various tetrahedral sites in good agreement with the average structural model for this mullite (Rehak et al. 1998). Satellite transition spectroscopy has also been used to study the Al configuration of sillimanite, a polymorph of Al2Si05 which is structurally related to mullite (Rehak et al. 1998). 

Another polymorph of AlaSiOs, kyanite, contains four crystallographically inequivalent AlOfi sites with widely differing quadrupolar interactions but spread over a relatively small chemical shift range. A battery of Al NMR techniques, including MAS at different fields, satellite transition spectroscopy (Smith et al. 1994), MQ MAS NMR (Alemany et al. 1999, 1999a) and double rotation (Xu and Sherriff 1993, Smith et al. 1994) has been used to resolve the four sites and allow the simulation of the eomplete spectrum (Figure 5.5B). 

Portland cement and high-alumina cements contain, in addition to calcium silicate phases, calcium monoaluminate, CaAl204 (or CA in cement chemist s shorthand, where C = CaO and A = AI2O3). The Al NMR spectra of this compound, in which the Al is exclusively in tetrahedral coordination, and a number of other calcium alu-minates have been determined (Muller et al. 1986), and more recently, using satellite transition spectroscopy (SATRAS) which has allowed the multiple tetrahedral sites in the various calcium aluminates to be distinguished (Skibsted et al. 1993). The NMR parameters for the synthetic aluminates and a number of their hydration products are shown in Table 5.4. 

Jager C (1994) Satellite transition spectroscopy of quadrupolar nuclei. In Solid-state NMR 11 inorganic matter, vol 31. Springer, Berlin Heidelberg New York... 

The satellite transition spectroscopy (SATRAS) approach, whereby the spectra of the satellite transitions are observed under MAS conditions and simulated to extract the relevant NMR information, is most generally applicable when the quadmpolar interaction is small. Shown in Figure 5 is an example of the spectra obtained by Trill et al. for a series of halide sodalites. " This method will also benefit from continued increases in available MAS rates. 

Ingwall, J.S. Measuring Cation Movements Across the Cell Wall Using NMR Spectroscopy Sodium Movements in Striated Muscle. Vol. 28, pp. 131-160 Jager, C. Satellite Transition Spectroscopy of Quadrupolar Nuclei. Vol. 31, pp. 133-170 Jonas, J. High Pressure NMR Studies of the Dynamics in Liquids and Complex Systems. 

Other relevant methods are (1) quadrupole nutation spectroscopy, a two-dimensional technique which allows the projection of the conventional spectrum in one dimension, and only quadrupolar information in the second frequency axis, (2) dynamic-angle spinning (DAS), in which the sample is spun sequentially rather than simultaneously (as in DOR) about two different magic axes and (3) satellite transition spectroscopy (SATRAS), which monitors... 

Satellite Transition Spectroscopy (SATRAS) [9,10] has been proven to be a useful technique to determine the NMR parameters of quadrupolar spin systems, in particular when the quadrupolar frequency Uq is so small that the structure of the central transition (CT) 1/2 —1/2 due to second-order effects is not resolved. In that case, reliable informa-... 

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