title: CP dynamics of heterogeneous organic material: characterization of molecular domains in coals.
abstract: Simplified equations are used in common approaches to describe cross polarization (CP) dynamics of solids. The CP behavior may be modulated by several nuclei interactions and physicochemical sample properties. At high magnetic fields and spinning speeds, these modulations can obscure the results. To elucidate their impact on the CP behavior of natural organic materials variable contact time (VCT) experiments were acquired with a high temporal resolution for two coal samples. The measurements were distinctly influenced by interfering fluctuations. Conventional approaches showed insufficient flexibility in terms of degrees of freedom to calculate the CP dynamics. The use of an original fundamental equation as model resulted in sufficient flexibility for such heterogeneous systems. The best results were obtained assuming a two component system. On these conditions a differentiation between amorphous and crystalline domains within the coal samples was enabled.
authors.affiliation: Lehrstuhl für Bodenkunde, Department für Okologie, Wissenschaftszentrum Weihenstephan, Technische Universität München, D-85350 Freising-Weihenstephan, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Abelmann
authors.forename: Kai Uwe
authors.initials: KU
authors.lastname: Totsche
authors.forename: Heike
authors.initials: H
authors.lastname: Knicker
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kögel-Knabner
mesh_terms: D000465:Algorithms; D002247:Carbon Isotopes; D003031:Coal / Q000032:analysis*; D045424:Complex Mixtures / Q000032:analysis* / Q000737:chemistry*; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry*; D013113:Spin Labels
chemical_list: D002247:Carbon Isotopes; D003031:Coal; D045424:Complex Mixtures; D009930:Organic Chemicals; D013113:Spin Labels