GLASS-LIKE BEHAVIOR IN SUPERCRITICAL FLUIDS : THE EFFECT OF CRITICAL SLOWING DOWN ON SOLUTE DYNAMICS

摘要: Compressible supercritical fluids exhibit extended density inhomogeneities which, due to their collective many-particle nature, fluctuate only very slowly, a phenomenon known as “critical slowing down.” Our computations demonstrate that these slowly fluctuating may remain effectively frozen on the time scale of fast dynamic processes such solute vibrational relaxation. Furthermore, we find given molecule experience any broad distribution static local solvent environments and each solute’s dynamical behavior will be controlled by its own environment. Consequently, an ensemble molecules relax with correspondingly lifetimes. Although inhomogeneous broadening effects are expected in amorphous solids glasses, this is first confirmation presence fluids.