title: Optimisation of excitation schemes for14N overtone MAS NMR using numerically exact simulations.
abstract: Numerically exact simulations of the14N overtone (14NOT) MAS NMR experiment are used to investigate the effects of the applied magnetic field strength as well as three types of excitation pulse. The results show that both the resolution and sensitivity of14NOTMAS NMR increase linearly with the applied static magnetic field strength. Standard RF excitation pulses are compared with frequency-swept WURST pulses as well as several composite pulses. WURST pulses are demonstrated to provide the largest bandwidths, while the direction of the frequency sweep is shown to be important when these pulses are used for the direct observation of14NOTsignals. A composite pulse is shown to provide the most efficient excitation overall, but only when applied on resonance. WURST excitation pulses are therefore the best option when studying a sample with unknown14N NMR parameters.
authors.affiliation: Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, M40, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Andreas
authors.initials: A
authors.lastname: Brinkmann
authors.affiliation: Institute for Frontier Materials, Deakin University, Waurn Ponds Campus, Geelong, Victoria 3220, Australia. Electronic address: luke.odell@deakin.edu.au.
authors.forename: Luke A
authors.initials: LA
authors.lastname: O'Dell
keywords: (14)N solid-state NMR; Composite pulses; Excitation pulses; Overtone spectroscopy; WURST pulses