title: Long-term stability of rotor-controlled MAS frequencies to 0.1 Hz proved by 14N MAS NMR experiments and simulations.
abstract: Experimental and simulated 14N MAS NMR spectra of the NH4+ ions in the two polymorphs, mS60 and mP60, of (NH4)2MoO4 are used to illustrate that a long-term stability of rotor-controlled MAS frequencies to 0.1 Hz can be achieved using commercial instrumentation (MAS speed controller and 7.5 mm MAS probe with a single marked rotor) attached to a highly pressure-stabilized air supply. A new modification of the STARS simulation software employs a Gaussian distribution for the experimental spinning frequency around the frequency set for the MAS speed controller. A simulated spectrum is then obtained by summation of several calculated spectra for evenly spaced spinning frequencies around the set frequency with relative weight factors corresponding to the Gaussian distribution.
authors.affiliation: Instrument Centre for Solid-State NMR Spectroscopy, Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark. hja@chem.au.dk
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Jakobsen
authors.forename: Anders R
authors.initials: AR
authors.lastname: Hove
authors.forename: Henrik
authors.initials: H
authors.lastname: Bildsøe
authors.forename: Jørgen
authors.initials: J
authors.lastname: Skibsted
authors.forename: Michael
authors.initials: M
authors.lastname: Brorson
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry*; D011846:Radio Waves; D015203:Reproducibility of Results; D012399:Rotation; D012680:Sensitivity and Specificity
chemical_list: D009584:Nitrogen