Structural Studies of Noncrystalline Solids Using Solid State NMR. New Experimental Approaches and Results

The term “glass” describes a state of matter that possesses most of the macroscopic and thermodynamic properties of a crystalline solid, while retaining the structural disorder and isotropic behavior typical of the liquid state. Cooling a liquid quickly below its freezing point under conditions that prevent thermodynamic equilibration results in the glassy state at a well-defined temperature T_g, where collective molecular motion is frozen abruptly. This “glass transition temperature” is a thermodynamic necessity and possesses the phenomenological appearance of a second order phase transition [1].