Premium
Application of proton field‐cycling NMR relaxometry for studying translational diffusion in simple liquids and polymer melts
Author(s) -
Flämig Max,
Hofmann Marius,
Lichtinger Anne,
Rössler Ernst A.
Publication year - 2019
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4823
Subject(s) - relaxometry , chemistry , intramolecular force , relaxation (psychology) , chemical physics , intermolecular force , polymer , diffusion , rotational diffusion , dispersion (optics) , proton , nuclear magnetic resonance , thermodynamics , spin echo , organic chemistry , molecule , physics , magnetic resonance imaging , medicine , psychology , social psychology , quantum mechanics , optics , radiology
With the availability of commercial field‐cycling relaxometers together with progress of home‐built instruments nuclear magnetic resonance relaxometry has gained new momentum as a method of investigating the dynamics in viscous liquids and polymer melts. The method provides the frequency dependence of the spin–lattice relaxation rate. In the case of protons, one distinguishes intramolecular and intermolecular relaxation pathways. Whereas the intramolecular contribution prevails at high frequencies and reflects rotational dynamics, the often ignored intermolecular relaxation contribution dominates at low‐frequency and provides access to translational dynamics. A universal low‐frequencies dispersion law holds which in pure systems allows determining the diffusion coefficient in a straightforward way. In addition, the rotational time constant is extracted from the high‐frequency relaxation contribution. This is demonstrated for simple and ionic liquids and for polymer melts.