Spectra of copper and europium β-diketonates in alcoholic solutions and transparent dielectrics

Abstract

We have used optical and EPR spectroscopy to study the mechanisms for color center formation in nanoporous glasses, polymethylmethacrylate, and alcoholic solutions containing ?-diketonate molecules: Cu(hfac)2, Ba(hfac)2, Pr(hfac)3, and Eu(fod)3. We have observed and studied the complex structure of the absorption bands in the 300 nm region belonging to the intraligand π-π* transition. Analogous results were obtained when studying the photoluminescence spectra of 5D0 → 7F0 transitions of Eu3+ ions and the EPR spectra of Cu2+ ions in matrices doped with Cu(hfac)2. We propose a model according to which for β-diketonate molecules (except for basic diketonates), a hydrolyzed form exists that is formed during synthesis of the polycrystalline powder due to the presence of water molecules. The model allows us to explain the spectral manifestations of β-diketonates in different matrices.