title: Fast amplitude-modulated pulse trains with frequency sweep (SW-FAM) in solid-state NMR of spin-7/2 nuclei.
abstract: We here investigate the sensitivity enhancement of central-transition NMR spectra of quadrupolar nuclei with spin-7/2 in the solid state, generated by fast amplitude-modulated RF pulse trains with constant (FAM-I) and incremented pulse durations (SW-FAM). Considerable intensity is gained for the central-transition resonance of single-quantum spectra by means of spin population transfer from the satellite transitions, both under static and magic-angle-spinning (MAS) conditions. It is also shown that incorporation of a SW-FAM train into the excitation part of a 7QMAS sequence improves the efficiency of 7Q coherence generation, resulting in improved signal-to-noise ratio. The application of FAM-type pulse trains may thus facilitate faster spectra acquisition of spin-7/2 systems.
authors.affiliation: Institute of Physics, University of Halle, Friedemann-Bach-Platz 6, DE-06108 Halle, Germany. thomas.braeuniger@physik.uni-halle.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Bräuniger
authors.forename: P K
authors.initials: PK
authors.lastname: Madhu