title: Distributions of transverse relaxation times for soft-solids measured in strongly inhomogeneous magnetic fields.
abstract: The single-sided NMR-MOUSE sensor that operates in highly inhomogeneous magnetic fields is used to record a CPMG (1)H transverse relaxation decay by CPMG echo trains for a series of cross-linked natural rubber samples. Effective transverse relaxation rates 1/T(2,short) and 1/T(2,long) were determined by a bi-exponential fit. A linear dependence of transverse relaxation rates on cross-link density is observed for medium to large values of cross-link density. As an alternative to multi-exponential fits the possibility to analyze the dynamics of soft polymer network in terms of multi-exponential decays via the inverse Laplace transformation was studied. The transient regime and the effect of the T(1)/T(2) ratio in inhomogeneous static and radiofrequency magnetic fields on the CPMG decays were studied numerically using a dedicated C++ program to simulate the temporal and spatial dependence of the CPMG response. A correction factor T(2)/T(2,eff) is derived as a function of the T(1)/T(2) ratio from numerical simulations and compared with earlier results from two different well logging devices. High-resolution T(1)-T(2) correlations maps are obtained by two-dimensional Laplace inversion of CPMG detected saturation recovery curves. The T(1)-T(2) experimental correlations maps were corrected for the T(1)/T(2) effect using the derived T(2)/T(2,eff) correction factor.
authors.affiliation: Technical University of Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania.
authors.forename: R I
authors.initials: RI
authors.lastname: Chelcea
authors.forename: R
authors.initials: R
authors.lastname: Fechete
authors.forename: E
authors.initials: E
authors.lastname: Culea
authors.forename: D E
authors.initials: DE
authors.lastname: Demco
authors.forename: B
authors.initials: B
authors.lastname: Blümich
mesh_terms: D003201:Computers; D007089:Image Enhancement; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D008422:Materials Testing / Q000379:methods*; D008853:Microscopy / Q000379:methods; D008962:Models, Theoretical; D012680:Sensitivity and Specificity