title: Swept-frequency two-pulse phase modulation (SWf-TPPM) sequences with linear sweep profile for heteronuclear decoupling in solid-state NMR.
abstract: Recently, a pulse scheme for heteronuclear spin decoupling in solid-state NMR, called swept-frequency two-pulse phase modulation (SW(f)-TPPM), was introduced which outperforms the standard TPPM and small phase incremental alteration (SPINAL) schemes. It has also been shown that the frequency-sweep profile can be varied to achieve optimal efficiency for crystalline and liquid-crystalline samples, respectively. Here we present a detailed comparison of the proton decoupling performance for SW(f)-TPPM sequences with tangential sweep profiles (SW(f) (tan)-TPPM) and linear sweep profiles (SW(f) (lin)-TPPM). Using the (13)CH(2) resonance of crystalline tyrosine as a model system, it is shown that linear profiles have a decoupling performance which is at least as good and in some instances slightly better than that obtained from tangential sweep profiles. While tangential sweep profiles require a tangent cut-off angle as an additional parameter, the lack of that parameter makes linear sweep profiles easier to implement and optimise.
authors.affiliation: Institute of Physics, University of Halle, Friedemann-Bach-Platz 6, 06108 Halle, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Vinod Chandran
authors.forename: P K
authors.initials: PK
authors.lastname: Madhu
authors.forename: Narayanan D
authors.initials: ND
authors.lastname: Kurur
authors.forename: Thomas
authors.initials: T
authors.lastname: Bräuniger
mesh_terms: D002247:Carbon Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D012015:Reference Standards; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D011522:Protons; D014443:Tyrosine