Application of fast amplitude-modulated pulse trains for signal enhancement in static and magic-angle-spinning 41,49Ti-NMR spectra

It is demonstrated that the use of fast amplitude-modulated RF pulse trains with constant (FAM-I) and incremented pulse durations (SW-FAM) leads to considerable sensitivity enhancement for the central-transition signal (via spin population transfer from the satellite transitions) for solid-state NMR spectra of titanium, Ti-47 (I = 5/2) and Ti-49 (I = 7/2). For the magic-angle spinning spectra of TiO2 and BaTiO3, the intensity of the Ti-49 central-transition line was more than doubled compared to simple Hahn-echo acquisition, while for the static case, enhancement factors of 1.6 (TiO2) and 1.8 (BaTiO3) were obtained. No lineshape distortions are observed in either MAS or static spectra of both compounds. Employment of the FAM and SW-FAM sequences should be useful in the routine acquisition of Ti-47,Ti-49 spectra, as the NMR signal can be detected much faster. (C) 2004 Elsevier Inc. All rights reserved.