期刊
JOURNAL OF MAGNETIC RESONANCE
卷 285, 期 -, 页码 47-54出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jmr.2017.10.008
关键词
Molecular motions; Polymers; Dipolar filter; Tikhonov regularization
资金
- Brazilian funding agency FAPESP [2009/18354-8, 2008/11675-0]
- Brazilian funding agency CNPq [312852/2014-2, 131489/2014-2, 401454/2014-2, 300121/2015-6]
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [08/11675-0] Funding Source: FAPESP
We present a simple H-1 NMR approach for characterizing intermediate to fast regime molecular motions using H-1 time-domain NMR at low magnetic field. The method is based on a Goldmann Shen dipolar filter (DF) followed by a Mixed Magic Sandwich Echo (MSE). The dipolar filter suppresses the signals arising from molecular segments presenting sub kHz mobility, so only signals from mobile segments are detected. Thus, the temperature dependence of the signal intensities directly evidences the onset of molecular motions with rates higher than kHz. The DF-MSE signal intensity is described by an analytical function based on the Anderson Weiss theory, from where parameters related to the molecular motion (e.g. correlation times and activation energy) can be estimated when performing experiments as function of the temperature. Furthermore, we propose the use of the Tikhonov regularization for estimating the width of the distribution of correlation times. (C) 2017 Elsevier Inc. All rights reserved.
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