Cooperative relaxation phenomenon

Another type of kinetics pattern currently under discussion is related to the so-called Mode-Coupling Theory (MCT) developed by Gotze and Sjogren [74], In the MCT the cooperative relaxation process in supercooled liquids and amorphous solids is considered to be a critical phenomenon. The model predicts a dependence of relaxation time on temperature for such substances in the form... 

In the glass transition temperature domain, a relaxation phenomenon assigned to the a-relaxation was observed as the cooperative reorientation motions of large segments containing backbone (CN) groups, as suggested by Fmukawa et al. [108]... 

The a-relaxation is related to the glass transition of the systems and for that reason this relaxation is also called dynamic glass transition. In general, the a-relaxation and the related glass transition phenomenon are not well understood, and the actual microscopic description of the relaxation remains unsolved besides it is a current problem in polymer science [41]. However, it is well accepted that the dynamics of the glass transition is associated with the segmental motion of chains being cooperative in nature... 

The question of the nature of the superconducting state in the radical-ion salts can still not be unambiguously answered even after more than 20 years of intensive research. In the conventional superconductors, the phenomenon can be explained through the BCS theory by the formation of Cooper pairs. Here, the attractive interaction between two electrons is mediated by phonons. The total spin of the Cooper pairs is S = 0, and their total orbital angular momentum is I = 0. The pair wave-function is an s-function. The concept of the Cooper pairs as spin singlets can evidently also be applied to the radical-ion salts. This can for example be shown by measurements of the NMR spin-lattice relaxation time in the superconducting state [3]. 

---