title: An analysis of phase-modulated heteronuclear dipolar decoupling sequences in solid-state nuclear magnetic resonance.
abstract: The design of variants of the swept-frequency two-pulse phase modulation sequence for heteronuclear dipolar decoupling in solid-state NMR is reported, their performance evaluated, and compared with other established sequences like TPPM and SPINAL. Simulations performed to probe the role of the homonuclear (1)H-(1)H bath show that the robustness of the decoupling schemes improves with the size of the bath. In addition, these simulations reveal that the homonuclear (1)H-(1)H bath also leads to broad baselines at high MAS rates. Results from a study of the SPINAL decoupling scheme indicate that optimisation of the starting phase and phase increment improves its performance and efficiency at high MAS rates. Additionally, experiments performed on a liquid crystal display the role of the initial phase in SPINAL-64 and sequences in the SW(f)-TPPM family.
authors.affiliation: Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India.
authors.forename: Rajendra Singh
authors.initials: RS
authors.lastname: Thakur
authors.forename: Narayanan D
authors.initials: ND
authors.lastname: Kurur
authors.forename: P K
authors.initials: PK
authors.lastname: Madhu
mesh_terms: D002247:Carbon Isotopes; D005998:Glycine / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D002247:Carbon Isotopes; D005998:Glycine