Optical Properties and Characterization of Eu 3+ Activated Pmma:Paac Copolymer Samples: Eu Concentration Effects
- PDF / 268,639 Bytes
- 7 Pages / 390.24 x 621.9 pts Page_size
- 11 Downloads / 178 Views
R. SOSA F., M. FLORES, R. RODRIGUEZ T. AND A. MU&OZ F. Physics Department Universidad Aut6noma Metropolitana-Iztapalapa, Distrito Federal, Mdxico PO BOX 55-532.
ABSTRACT Samples of Eu 3+-activated PMMA:PAAc copolymers were prepared in order to investigate their spectroscopic properties. The densities, refractive indices, UV-Visible absorption and emission spectra and fluorescence decay times were obtained experimentally. These data were used in conjunction with Judd-Ofelt theory to calculate the spontaneous emission probabilities and branching ratios, as a function of the europium content. The range of the concentration was 0.1 to 2.5 % mol. Our results are combined with previous information on the optical properties of rare-earth activated polymers in order to get a better understanding of the role played by the Eu 3' ions on the polymerization process in our samples.
INTRODUCTION The incorporation of rare earth (RE) ions in different host materials can impart to them valuable optical properties. This fact has produced great interest in the last few years and makes important to provide new materials with composition flexibility that includes RE ionsill. Nevertheless, even when luminescent polymers are attractive due to their possible use in technological applications, only few works have been done on the optical properties of such kind of systems, when they have been activated with lanthanide ions 2' 3 ]. On this respect, in this work are presented the results of a detailed experimental study on the effects of Eu 3 + ions on the optical properties of PMMA:PAAc copolymers, in order to get a better understanding of the effects of the europium ions on the polymerization process and the optical properties of the host material.
311 Mat. Res. Soc. Symp. Proc. Vol. 558 ©2000 Materials Research Society
EXPERIMENTAL
Freshly distilled monomers of methyl methacrylate (MMA) (Aldrich Chem. Co.) and acrylic acid (AAc) (Aldrich Chem. Co.) were mixed with 1-butanol (Baker Chem. Co.) which is used as medium. The initiator was 2, 2'-azo bis isobutire nitrile (AIBN) in a molar relation 1:1000 respect to monomers. The europium salt (EuCI3) was added to the mixture under agitation until it dissolves; the concentration of Eu 3+ ions was varied from 0.1% to 3mol %, being the salt concentration practically the saturation concentration. For all the samples, the monomers were introduced in a 1:1 molar relation. The polymer solution was dried at 110 C under reduced pressure and the result sample was collected for use it for to determined the refractive index of the material. The dried polymer was thermoformed at 120 C, under moderate pressure to produce small discs of 1.2mm thickness. All measurements performed in this work were taken on samples having the shape of disk of 15mm in diameter and 1.2 mm in thickness. Continuos fluorescent spectra were obtained with a Perkin-Elmer model 650-IOS spectrofluorometer equipped
with a 150W Xenon lamp. The photoluminescence
measurements were also carried out using a Perkin-Elmer fluorescence s
Data Loading...
