849 Russian Physics Journal, Vol. 53, No. 8, 2011 OPTICAL PROPERTIES OF CdS/MMA DISPERSIONS AND CdS/PMMA NANOCOMPOSITES PREPARED BY ONE-STEP, SIZE- CONTROLLED SYNTHESIS A. A. Biryukov, T. I. Izaak, E. Yu. Gotovtseva, UDC 541.64:539.2:546.48 I. N. Lapin, A. I. Potekaev, and V. A. Svetlichnyi Results of investigations into the optical properties of semiconductor quantum dots (including absorption, fluorescence, and nonlinear scattering) in CdS/MMA dispersions and CdS/PMMA composites prepared by one-step, size-controlled synthesis in a monomer medium are presented. It is demonstrated that selective optical excitation during synthesis of CdS nanoparticles in the monomer medium allows the particle sizes to be controlled. It is demonstrated that changes of the sulfur/cadmium ratio in the reaction mixture influence significantly the fluorescent properties of particles. Nonlinear scattering of the synthesized media is investigated, and it is revealed that scattering in optically homogeneous composites is much weaker than in dispersions where agglomerates with sizes up to 100 nm are presented. Keywords: quantum dots, size-controlled synthesis, CdS/MMA nanoparticle dispersions, CdS/PMMA nanocomposite, spectral and luminescent properties, nonlinear scattering. INTRODUCTION The media comprising quantum dots (QD) of A 2 B 6 semiconductors belonging to chalcogenides of transitive metals are unique materials whose optical properties depend on the nanoparticle sizes and shapes [1–3]. Nowadays QD find application as fluorescent labels in biological media [4, 5] and bio- and chemical sensors [6, 7] substituting for other materials, in particular, fluorescent organic dyes, because they have higher photostability, radiation efficiency [5], and sensitivity in comparison with these materials. Other promising directions of QD application in optical technologies are their application as active elements of solar cells [8] and amplifying [9] and nonlinearly absorbing media [10] and components of media for multiphoton microstereolithography increasing nonlinear susceptibility during synthesis and providing unique fluorescent properties of synthesized 3D microstructures [11]. Of practical interest for these applications are solid hybrid materials comprising organic (polymer matrix) and inorganic components (nanoscale particles). In most cases, these materials are synthesized in several steps. QD dispersions are first prepared in an organic solvent, and then QD are transferred to a monomer medium [12–14]. This step makes the procedure of synthesis much more expensive and calls for evaporation of the initial solvent not always possible without influencing the QD properties. Therefore, the development of one-step procedure of size-controlled synthesis of dispersions from particles of chalcogenides of transitive metals in acryl monomers is an urgent problem. In [15] it was demonstrated that macromolecules of optically transparent polymer – polymethylmethacrylate (PMMA) – can stabilize cadmium sulfide nanoparticles synthesized in a methylmethacrylate (MMA) medium. Moreover, the rate of particle aggregation depends on the molecular mass of the polymer: PMMA molecules with short chains have higher stabilizing ability. A method of one-step, size-controlled synthesis of CdS/PMMA nanocomposites was suggested in [15]. V. D. Kuznetsov Siberian Physical-Technical Institute of Tomsk State University, Tomsk, Russia, e-mail: svet@spti.tsu.ru. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 74–80, August, 2010. Original article submitted March 15, 2010. 1064-8887/1 /5308-0849 ©201 Springer Science+Business Media, Inc. 1 1