The ubiquitous nature of sulfur in organic, inorganic, poly-average these effects. Line narrowing can be attained through partial averaging of the second-order quadrupolar meric, and biological systems, coupled with the sizable presence of sulfur in many important industrial materials, pro-interactions using MAS (8) or variable-angle sample spinning (9). In theory, complete averaging can be achieved vides compelling reasons for the development of 33 S NMR methods. Although a considerable amount of work with 33 S using dynamic-angle spinning (10), double rotation (11), or multiple-quantum excitation (12, 13). NMR has been published (1), the only detailed solid-state 33 S NMR study was published in 1986 by Eckert and Yesi-
The solid-state 33 S NMR spectra of several sulfur-containing compounds obtained at 14.1 T with high-speed MAS nowski (2). In that work, they studied second-order quadrupolar broadening effects on the static lineshape of the central is shown in Fig. . Reasonably sharp resonances are observed for most of the materials. Typically, resonance line-(/1/2 } 01/2) transition. The broad lines reported for the many sulfur species described in Ref.
(2) may have widths are 10-fold narrower than those previously reported for these compounds without sample spinning. The line nar-discouraged further work on applications of solid-state 33 S NMR. In the almost 10 years since that initial publication, rowing is much greater than expected from the increased field strength (14.1 T in this work compared to 11.75 T used very little new work has been published in the area (3-5). In this Communication, we report how improvements in earlier). Most of the line narrowing arises from averaging of the chemical-shift anisotropy (CSA), dipolar coupling, NMR instrumentation combined with high-speed magicangle spinning (MAS) and high field permit the routine and second-order quadrupolar interactions. While complete averaging of the second-order quadrupolar interactions re-observation of relatively narrow 33 S lines from natural-abundance samples of various inorganic sulfur species.
quires the equivalent of sample spinning around two differ-33 S, with nuclear spin I Γ
3 2 and 0.76% natural abundance, ent axes, MAS at very high field can provide adequate line narrowing to obtain spectra which can be used to distinguish is the only NMR-detectable isotope of sulfur. These properbetween sulfur species. Consequently, relatively good specties, combined with a low magnetogyric ratio, lead to a tra can be obtained in a reasonable amount of time; for receptivity that is about 10 05 compared to that of 1 H (6). For all but the most symmetric sulfur species, the relatively example, the spectrum in Fig. was obtained in only 30 large electric quadrupole moment produces efficient relaxminutes. This same sample required 20 hours of signal averation which leads to broad lines in the liquid state, very aging at 4.7 T to obtain a spectrum of comparable signaloften precluding the resolution of separate resonances from to-noise, despite the fact that about ten times the amount of distinct sulfur species in solution. In the solid state, the outer sample was used on the lower-field instrument. (03/2 } 01/2 and /1/2 } /3/2) transitions are usually
The line narrowing observed for materials whose spectra broadened beyond detection by quadrupolar interactions, but are shown in Fig. appears to be a general phenomenon. the central (01/2 } /1/2) transition, to a first approxima-Table summarizes the results obtained from several inortion, is unaffected by quadrupolar interactions. In cases ganic sulfur-containing salts in which sulfur has a variety where the quadrupolar interaction is comparable to the resoof electronic symmetries and for which solid-state 33 S NMR nance frequency, second-order quadrupolar effects can lead data have appeared in the literature. In all cases, approxito a broad pattern from the central transition, with a width mately an order of magnitude reduction in linewidth was proportional to 1/B 0 (7). Various techniques can be used to achieved when compared with the analysis of static samples obtained earlier (2). In that work, several of the samples were run without sample spinning, yielding linewidths that