title: Sensitivity considerations in polarization transfer and filtering using dipole-dipole couplings: implications for biomineral systems.
abstract: The robustness and sensitivities of different polarization-transfer methods that exploit heteronuclear dipole-dipole couplings are compared for a series of heterogeneous solid systems, including polycrystalline tetrakis(trimethylsilyl)silane (TKS), adamantane, a physical mixture of doubly (13)C,(15)N-enriched and singly (13)C-enriched polycrystalline glycine, and a powder sample of siliceous marine diatoms, Thalossiosira pseudonana. The methods were analyzed according to their respective frequency-matching spectra or resultant signal intensities. For a series of (13)C{(1)H} cross-polarization experiments, adiabatic passage Hartmann-Hahn cross-polarization (APHH-CP) was shown to have several advantages over other methods, including Hartmann-Hahn cross-polarization (HHCP), variable-amplitude cross-polarization (VACP), and ramped-amplitude cross-polarization (RACP). For X-Y systems, such as (13)C{(15)N}, high and comparable sensitivities were obtained by using APHH-CP with Lee-Goldburg decoupling or by using the transferred-echo double resonance (TEDOR) experiment. The findings were applied to multinuclear (1)H, (13)C, (15)N, and (29)Si CP MAS characterization of a powder diatom sample, a challenging inorganic-organic hybrid solid that places high demands on NMR signal sensitivity.
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Christiansen
authors.forename: Niklas
authors.initials: N
authors.lastname: Hedin
authors.forename: Jan D
authors.initials: JD
authors.lastname: Epping
authors.forename: Michael T
authors.initials: MT
authors.lastname: Janicke
authors.forename: Yolanda
authors.initials: Y
authors.lastname: del Amo
authors.forename: Mark
authors.initials: M
authors.lastname: Demarest
authors.forename: Mark
authors.initials: M
authors.lastname: Brzezinski
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Chmelka
mesh_terms: D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry*; D002247:Carbon Isotopes; D005374:Filtration / Q000379:methods; D008903:Minerals / Q000032:analysis* / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001704:Biopolymers; D002247:Carbon Isotopes; D008903:Minerals; D011522:Protons