Abstract
Artificial polarization effects on two practically important applications of the title color center, namely laser light generation and adsorbate-substrate interactions are investigated by using quantum mechanical CIS and DFT ab initio methods. Clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surface, and ions that were the nearest neighbors to the defect site were allowed to relax to equilibrium to calculate the optical properties. The positive point charges surrounding the border anions of the "small" clusters were replaced by "real" cations to account for artificial polarization effects. The dependence of the calculated transition energies of F-A1:Sr2+ lasers and related optical properties such as optical-optical conversion efficiency, relaxed excited states of the defect-containing surface, orientational destruction of the point defect, recording sensitivity, and the Glasner-Tompkins empirical rule on artificial polarization effects was examined. The dependance of the adsorption energies of NO at NaCl (001) surface, as well as the coadsorption of NO, and the charge transfer reactions between NO and the paramagnetic chlorine vacancy on artificial polarization effects was also examined and the results were explained in terms of electrostatic potential curves. Some of the calculated properties were found to be sensitive to artificial polarization effects while others were found to be insensitive providing a support to the relatively small cluster models. (c) 2007 Elsevier B.V. All rights reserved.