title: Controlling coherence using the internal structure of hard pi pulses.
abstract: The tiny difference between hard pi pulses and their delta-function approximation can be exploited to control coherence. Variants on the magic echo that work despite a large spread in resonance offsets are demonstrated using the zeroth- and first-order average Hamiltonian terms, for 13C NMR in 60C. The 29Si NMR linewidth of silicon has been reduced by a factor of about 70,00 using this approach, which also has potential applications in magnetic resonance microscopy and imaging of solids.
authors.affiliation: Department of Physics, Yale University, New Haven, Connecticut 06511, USA.
authors.forename: Yanqun
authors.initials: Y
authors.lastname: Dong
authors.forename: R G
authors.initials: RG
authors.lastname: Ramos
authors.forename: Dale
authors.initials: D
authors.lastname: Li
authors.forename: S E
authors.initials: SE
authors.lastname: Barrett