Progress in understanding of mechanisms of RE3+-excited states nonradiative relaxation in crystals

Optical properties and site distribution of Cr3+ ions in alkali-disilicate glasses

“…The model proposed by Gapontsev et al [8] and Sirtlanov [9] for the Cr 3+ ions site distribution considers only one parameter, the zero-phonon energy parameter O; corresponding to the energy difference between the minima of the ground and the first excited electronic states (see Fig. 1).…”

“…This model allows one to analyse the absorption and emission band shapes and the transition probabilities between the ground and the excited states. Furthermore, the Cr 3+ site distribution can be taken into account in this model [4,7,8,11,14,[16][17][18]. In some works [4,8,11] an harmonic approximation with linear electron-lattice coupling between the ground and the excited levels has been considered, with site-to-site changes in the octahedral crystal-field parameter 10 Dq or equivalently, in the zero-phonon energy parameter O (see Fig.…”

“…The strong coupling between the Cr 3+ ion and the environment and consequently the high Svalue expected in this transition, allows us to consider as Gaussian the absorption and emission spectra for a particular site [8,9], i.e. …”

“…The goal is to develop a simple model that may be able to describe properly the experimental results, considering the fact that the inherent disorder in the glasses affects the spectroscopic properties of the optically active ions. In this sense, the optical properties of the Cr 3+ ions in alkali silicate glasses have been analysed in this work taking as the starting point the single configurational coordinate model (SCCM) [12] and considering a Gaussian site distribution characterised by the 10 Dq crystal-field parameter [8,9,13]. Other authors also include the assumption of a sitedependent electron-lattice coupling S and consequently a value distribution for this parameter [14].…”

“…Despite the numerous works devoted to analyse this effect, unresolved aspects still remain [4,5,[8][9][10][11]. The goal is to develop a simple model that may be able to describe properly the experimental results, considering the fact that the inherent disorder in the glasses affects the spectroscopic properties of the optically active ions.…”