title: Frequency- and phase-modulated heteronuclear decoupling in rotating solids.
abstract: The mechanism of heteronuclear dipolar decoupling by the TPPM sequences, proposed by Bennett et al. (J. Chem. Phys. 103 (1995) 6951) is investigated by comparison with a modified pulse sequence, called TPFM, that uses frequency instead of phase modulation. By combining frequency and phase modulations, circularly modulated sequences are designed. The fact that only the left-handed modulation sequence FMPML leads to improved proton decoupling, while the right-handed modulation sequence FMPMR is ineffective, proves that the efficient decoupling is caused by a secondary resonance effect.
authors.affiliation: Laboratorium für Physikalische Chemie, Eidgenössische Technische Hochschule, Zürich, Switzerland.
authors.forename: Z
authors.initials: Z
authors.lastname: Gan
authors.forename: R R
authors.initials: RR
authors.lastname: Ernst
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005561:Formates / Q000737:chemistry; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D011522:Protons; D011846:Radio Waves; D012399:Rotation
chemical_list: D005561:Formates; D011522:Protons; C030544:formic acid