Slow molecular dynamics in binary organic glass formers

Effects of Various Types of Molecular Dynamics on 1D and 2D 2H NMR Studied by Random Walk Simulations

“…As mentioned above, these investigations are relevant for a forthcoming analysis of experimental results on the ␤ process in supercooled liquids and glasses (21). In what follows, we try to make such restricted motions visible by applying 2D 2 H NMR in time domain.…”

“…In all simulations, the various parameters describing damping and excitation effect are kept fixed. They are chosen in such a way that 1D spectra similar to experimental ones result as will be described in detail elsewhere (21). For example, ⌬ p ϭ 3.8 s is used in all simulations.…”

“…For that purpose, we simulate cos-cos correlation functions assuming reorientations on a cone. The cos-cos instead of the sin-sin correlation functions are now calculated since, for experimental reasons concerning spin-lattice relaxation during the mixing time (19,21), they were considered in our study of the ␤ process. The opening angle of the cone is set to ϭ 6°in all RW simulations where this particular value is motivated by our experimental findings (21,42).…”

“…In a forthcoming publication, we will study complex molecular dynamics connected with the primary and secondary relaxation in supercooled liquids and glasses by applying 1D and 2D 2 H NMR experiments (21). However, due to the complicated properties of these motions and the structure of the involved pulse sequences, unexpected findings appear in this inquiry which make a straightforward analysis of the results impossible.…”

“…We use dynamical models reflecting the actual molecular dynamics in supercooled liquids and glasses to some extent. This choice is intended to allow an easy comparison of the results obtained in the RW simulations and in our 2 H NMR experiments (21), respectively. However, we do not plan to describe the experimental findings quantitatively, but rather we will try to keep the models as simple as possible in order to stress the general aspects.…”