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Yes. Glass, even at room temperature, is a liquid: the interatomic bonds areweak are and constantly breaking and reforming. These bonds are infact an interaction of (or, sharing of) the valence electrons ofadjacent atoms. (In metals this sharing of electrons results in electrical conduction. For example, in a length of copper wire, the individualelectrons at one end of the wire will, in theory, eventually migrate tothe other end of the wire, due to random motion and without the application of an outsideforce). The inter-atomic bonding structure within the bulk of a material placesphysical constraints upon the valence electrons. Therefore, if youactivate a color center (by any means) the alteration in the valence shellwill be either stable (unchanging with time) or meta-stable (will changegradually with time). The stronger the interatomic structure (or 'lattice'in the case of a true crystal which, unlike a glass, is a solid) the morestable the change. The change can however be reversed by weakening theinter-atomic bonds which will allow the formation of new, lower energybonds (atoms will break their initial bonds and reform bonds with other neighbors). This can be accomplished simply by the application of heat. In practice,the temperature required for complete color deactivation in an amorphous material (such as a glass) is its annealing temperature. Therefore, simply annealing a piece of glass will deactivate the color centers.

Material properties, both in bulk and in single molecular-sized particles,are derived from the knowledge of the molecular structure. Specifically, the molecular structure and the molecular configuration (structure of way the molecules are bonded)determine the properties of the materials. Crystallographic and physicalproperties of solids and polymers are determined by their molecular structure. For example, crystalline substances are organized by long-range order. The molecules in crys-talline substances are arranged in a regular manner and the crystalline structurevaries with the size of the crystal. A molecular-size crystal with a threshold periodicity of 12nm (300mmsol size) is known as a 12-crystal. In this crystal, each molecule has a 12-foldsymmetry and the crystalline structure is the result of cooperative motion (coopera-tionary motion-the tendency of the molecules to move in a specific way)of the individual molecules. d2c66b5586