FIRST-SATELLITE SPECTROSCOPY, A NEW METHOD FOR QUADRUPOLAR SPINS

A new spectroscopic method that detects only the +/-3/2 <-> +/-1/2 tra nsitions (i.e., first satellites) of half-integer quadrupolar nuclei i n solids is presented. The technique is based on a central-transition signal enhancement method that makes use of adiabatic radio-frequency sweeps. A plot of the enhanced central-transition signal amplitude ver sus the stop frequency of the sweep is an integrated version of the fi rst-satellite spectrum. To find the quadrupole parameters, one can fit this integrated spectrum directly or differentiate the data to reveal the traditional spectrum (of the first satellites). The technique is demonstrated for Al-27 in Al2O3 and Nb-93 in LiNbO3. First-satellite s pectroscopy is more sensitive than other methods for studying wide, qu adrupolar broadened spectra. The technique is easier to perform experi mentally. Since the resulting spectra contain only the innermost satel lites, the experimental data are considerably simpler and easier to in terpret in cases of two or more inequivalent sites. (C) 1996 Academic Press, Inc.