Dipolar filtered magic-sandwich-echoes as a tool for probing molecular motions using time domain NMR

Autor(es)

Filgueiras, Jefferson G. ^[1] ; da Silva, Uilson B. ^[1] ; Paro, Giovanni ^[1] ; d'Eurydice, Marcel N. ^[2] ; Cobo, Marcio F. ^[1] ; deazevedo, Eduardo R. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, POB 369, BR-13560970 Sao Carlos, SP - Brazil

^[2] Victoria Univ Wellington, Sch Chem & Phys Sci, POB 600, Wellington - New Zealand

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MAGNETIC RESONANCE; v. 285, p. 47-54, DEC 2017.
• Citações Web of Science: 5

Resumo

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. (AU)

• Processo FAPESP: 08/11675-0 - Métodos de RMN para estudos de materiais com alta mobilidade molecular: aplicações a polímeros eletroluminescentes e nanocompostos de intercalação
• Beneficiário: Márcio Fernando Cobo
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 09/18354-8 - Dinâmica e estrutura de sistemas poliméricos estudados por ressonância magnética nuclear
• Beneficiário: Eduardo Ribeiro de Azevedo
• Modalidade de apoio: Auxílio à Pesquisa - Regular