The Viscosity and Temperature Dependence of (1)H T(1)-NMRD of the Gd(H(2)O)(8)(3+) Complex

Water proton T(1)-NMRD profiles of the Gd(H(2)O)(8)(3+) complex have been recorded at three temperatures and at four concentrations of glycerol. The analysis is performed using both the generalized Solomon-Bloembergen-Morgan (GSBM) theory, and the stochastic Liouville approach (SLA). The GSBM approach uses a two processes dynamic model of the zero-field splitting (ZFS) correlation function whereas SLA uses a single process model. Both models reproduce the proton T(1)-NMRD profiles well. However, the model parameters extracted from the two analyses, yield different ESR X-band spectra which moreover do not reproduce the experimental ESR spectra. It is shown that the analyses of the proton T(1)-NMRD profiles recorded for a solution Gd(H(2)O)(8)(3+) ions are relatively insensitive to the slow modulation part of dynamic model of the ZFS interaction correlation function. The description of the electron spin system results in a very small static ZFS, while recent ESR lineshape analysis indicates that the contribution from the static ZFS is important. Analysis of proton T(1)-NMRD profiles of Gd(H(2)O)(8)(3+) complex do result in a description of the electron spin system but these microscopic parameters are uncertain unless they also are tested in a ESR-lineshape analysis.