SPECTRAL HOLE-BURNING IN CRYSTALLINE EU2O3 AND Y2O3-EU3+ NANOPARTICLES

Optical dephasing of nanoparticles of Eu2O and Y2O3:Eu3+ is studied, u sing transient spectral hole burning? as a function of temperature and particle size, d. A strongly enhanced optical dephasing rate is obser ved whose magnitude depends on 1/d(2). This is interpreted as an enhan cement of the electron-phonon interaction. A calculation for the two-p honon Raman scattering rate, which includes a smoothed phonon density of states for a nanoparticle, describes the nearly exponential tempera ture dependence of the hole line width, but does not properly describe the particle size dependence. A more complete theory which takes into account the spatial dependence of the amplitude of the phonon surface modes is required. (C) 1998 Elsevier Science B.V. All rights reserved .