Combined Reduced 4D 13C Exchange and 1H Spin Diffusion Experiment for Determining the Length Scale of Dynamic Heterogeneities

Molecular dynamics in solid polymers

“…New experiments obtained by adding extra mixing times and evolution periods in the stimulated-echo pulse sequence have also made it possible to obtain multiple time correlation functions. These techniques were used to elucidate the origin of the non-exponential behavior of the correlation functions that characterize the molecular motions at temperatures around the glass transition temperatures of these systems [68,69,75,92,118,119]. The results revealed that the nonexponentiality in the correlation functions is associated with dynamic heterogeneity with lifetimes comparable to that of the a-relaxation, and their sizes were estimated [69,119].…”

The defect diffusion model, scaling, EV*/H* and monomer volume and correlation lengths for glass-formers

“…Certainly the size of the immobile regions should be directly related to ξ DDM and the discussions of the NMR experiment in Refs. [8][9][10] indicate that ξ 4D3CP is a measure of the diameter of the slow regions. Table 1 and Fig.…”

“…Considerable effort in recent years has focused on attempting to determine a dynamic heterogeneity length scale in glass-forming liquids. Listed in Table 1 are the experimental values for the dynamic heterogeneity length scale, ξ 4D3CP , for four liquids measured using the 4D3CP NMR method pioneered by Tracht et al [8][9][10][11]. These four liquids have been previously analyzed by Qui and Ediger [12].…”

“…In the present paper, it is shown how the phenomena related to scaling are natural consequences of the DDM. Finally, the DDM is used to calculate correlation lengths and the results are compared with experimental dynamical correlation lengths measured using the 4D3CP solid state NMR method [8][9][10][11][12].…”

Multiple-Time Correlation Functions in Spin-3/2 Solid-State NMR Spectroscopy

“…or those with some or all of the sine functions replaced by cosine functions were given elsewhere for spin-1/2 and spin-1 nuclei (37,43,44). The factor B depends on the pulse lengths and the coherence pathways chosen in a particular implementation.…”