Elementary Electronic Excitations in Pure Sodium Silicate Glasses

Abstract

Electronic structure in high-purity sodium silicate glasses is studied. The spectral dependence of the relative quantum yield of the external and internal photoemission, the luminescence excitation spectra, the luminescence decay, and the polarization degree of the luminescence are measured.The luminescence band at 3.4 eV is created by the intrinsic anisotropic luminescence centre labelled L, whose absorption causes the fundamental absorption tail of high-purity silicate glasses, where the localized elementary excitations are created by photons. The phonon-assistent or tunneling delocalization processes produce colour centres. An electron release from the L-centre leads to the creation of the Hz-centre. An electron capture of the L-centre results in the El-centre. A model of the structure Na+ -0--Si 5 is proposed for the L-centre. Hence the structure for the ETcentre model will be NaO ... 0--Si e, but for the H;-centre i t will be Na+ ... 0 -Si =. The pair of Ec-and Hi-centres can probably recombine in a tunneling process.

Luminescence of modified nonbridging oxygen hole centers in silica and alkali silicate glasses

“…The specific feature of the third band observed in the pulsed cathodoluminescence spectra of the two-alkali silicate glasses upon excitation with a pulsed electron beam (see attributed to the L 2 center, has not been revealed in the steady-state photoluminescence spectra [2,18,[26][27][28][29]. It can be assumed that the possibility of observing the third band in the spectra is associated with the high sensitivity of the pulsed cathodoluminescence method, which exceeds the sensitivity of the photoluminescence method by several orders of magnitude.…”

Nonlinear photosensitivity of photo-thermo-refractive glass by high intensity laser irradiation

“…An area of blue luminescence can be seen in the glass bulk. This blue luminescence in silicate glasses results from recombination of intrinsic electron and hole centers produced by glass matrix ionization [12,13]. It was found that the area emitting this luminescence corresponds to the area of refractive index change after heat treatment.…”

Structure and luminescence of intrinsic localized states in sodium silicate glasses

“…Sodium silicate glasses are known to luminesce under ultraviolet and x-ray irradiation in a wide range of temperatures with a maximum luminescence energy of 3.4 eV [7]. Trukhin et al [8] have measured the excitation spectra, the kinetics, and the degree of polarization of luminescence in high-purity sodium silicate glasses under excitation with ultraviolet light with photon energies exceeding 5.5 eV [see Fig. 1(a)].…”

“…They concluded that the luminescence is caused by the intrinsic anisotropic structural motif in the glass, labeled L center, which is also responsible for the fundamental absorption edge of high-purity silicate glasses. This luminescence can be caused also by the decay of unstable color centers as a result of thermostimulated processes [7] or tunneling recombination of electron and hole centers [8,9].…”