Optical properties of CuCl particles in fluorozirconate glass

Optical extinction spectra of CuCl particles in a fluorozirconate glass whose composition is close to that of ZBLAN20 (53% ZrF4, 200/0 BaF2, 4% LaF3, 3% AlF3, and 20% NaF) are reported. Spectra show a sharp but structured band at 375 nm at room temperature which is resolved into two lines at 378 and 386 nm at 15 K. These two lines are attributed to the free exciton states Z(1.2), Z(3) of CuCl. Spectra are compared with calculations of optical extinction efficiency of spherical CuCl particles, based on Mie scattering theory. Calculations show that the shape of extinction spectra depends markedly on particle radius for radii above about 20 nm, and that the shape may thus be used to estimate the mean particle size. (C) 1998 Published by Elsevier Science B.V. All rights reserved.