The Urbach rule for the PbO-SiO2 glasses

Resonance vibrations of F- and F+- centers in α-Al2O3crystals

“…The discussed comparison is well justified considering a dominant contribution of localized vibrations to the dynamics of the processes involving defects of the imperfect lattice. From this and the performed calculations it may concluded that the effective vibrations revealed in [12,20] are due to the induced localized vibrations of the Asymmetry on aluminum atoms in the 1 st and 2 nd coordination spheres nearest to F + -and F-centers. Directions of the displacements of Al (1) and Al(2) ions are just shown in Figure 1.…”

“…At the same time, the table contains experimental estimates of the frequency of the effective phonons governing the temperature behavior of the optical absorption and luminescence bands of the centers under study in α-Al 2 O 3 . The measurements [12,20] provide just rough estimates of the averaged frequency of vibrations in the context of the single-phonon approximation. Nevertheless, the calculated and experimental estimates are in satisfactory mutual agreement, see Table 1.…”

Radiation-Induced Centers in Lead Silicate Glasses Irradiated by Stationary and Pulsed Electron Beams

“…The main characteristics determining the complex of the optical and electronic properties of solid-state materials are the position and shape of the ultraviolet boundary of the fundamental absorption that depend in a complex way on the external factors (temperature, mechanical loading, and irradiation) [3][4][5][6]. In amorphous materials, the nature of the fundamental absorption edge determines the main optical properties not only in the volume, but also in thin surface layers, including the photoemission activity of the surface and the efficiency of photostructural transformations.…”

Analysis of the Nonselective Spectra of Photostimulated Electron Emission from the Surface of Irradiated Dielectrics

“…The characteristic Urbach energy E 0 is associated with the degree of structural disordering in the lattice and usually weakly depends on the radiation action [10,11]. The value of E 0 can change considerably only under ultrahigh doses of particle bombardment when considerable structural disturbances arise and amorphization of the crystal structure takes place, which finally leads to a change in the density of electronic states in the band tails of the crystal matrix.…”