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2.4. Results and discussion 211.51.0n-hexadecane1/T 1[s -1 ]0.5TMOS0.02.0x10 -6 4.0x10 -6 6.0x10 -6 8.0x10 -6 1.0x10 -5η mix/ T [Pa s K -1 ]Fig. 2.6: Reciprocal T 1 (mono-exponential) of the TMOS/n-hexadecane mixtures as a functionof the viscosity-temperature ratio, η mix /T . T is fixed at 25 ◦ C.Table 2.1: Fitting parameters for the relaxation time model of the pure liquids.n-hexadecane TMOSτ ′ [ps] 0.052 1.64E A [kJ mol −1 ] 15.2 2.46τ c,eff [ps] at 20 ◦ C 26.7 4.49used (not presented here), which seems acceptable given the value of the self-diffusioncoefficient for the pure liquids (i.e. 1.59×10 −9 m 2 s −1 for TMOS and 0.40×10 −9 m 2 s −1for n-hexadecane at 25 ◦ C).The intra-molecular part of the relaxation contains the effective correlation time τ c,effwhich is found by an optimization process as follows. For both species the correlationtime τ c,eff as defined in Eq. 2.8 is assumed to be independent of concentration, thereforethe term is derived from the experimental data of pure TMOS and pure n-hexadecane,respectively. The predicted inter-molecular term is subtracted from the experimental,total T 1 for each temperature. Then the remainder is fitted as a function of temperaturewith Eqs. 2.7 and 2.8. The summation term ∑ r −6ij is estimated by considering a rigidmolecular model for each species. The resulting fits for TMOS and n-hexadecane, yieldingthe unknown parameters E A and τ ′ (see Table 2.1), are shown in Figure 2.4 as the solidcurves. The excellent fit indicates that the model equations adequately describe the spinlatticerelaxation of the pure liquids.Finally, the total relaxation times in the mixture are calculated (defined by Eqs. 2.14and 2.15) using the obtained fitting parameters (see Table 2.1). The Saturation Recoverydecay is subsequently constructed as given by Eq. 2.16, and the result is fitted with