CP dynamics of heterogeneous organic material:: characterization of molecular domains in coals

被引：18

作者：

Abelmann, K ^{[1
]}

Totsche, KU ^{[1
]}

Knicker, H ^{[1
]}

Kögel-Knabner, I ^{[1
]}

机构：

[1] Tech Univ Munich, Wissenschaftszentrum Weihenstephan, Lehrstuhl Bodenkunde, Dept Okol, D-85350 Freising Weihenstephan, Germany

来源：

SOLID STATE NUCLEAR MAGNETIC RESONANCE | 2004年 / 25卷 / 04期

关键词：

C-13; NMR; cross polarization dynamics; rotating frame relaxation; organic material; coal;

D O I：

10.1016/j.ssnmr.2003.10.003

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

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. (C) 2003 Elsevier Inc. All rights reserved.

引用

页码：252 / 266

页数：15

共 42 条

[1] CROSS POLARIZATION AND MAGIC ANGLE SAMPLE SPINNING NMR-SPECTRA OF MODEL ORGANIC-COMPOUNDS .1. HIGHLY PROTONATED MOLECULES [J].