ON THE DEPOSITION OF LANGMUIR-BLODGETT-FILMS OF Q-STATE CDS NANOPARTICLES THROUGH ELECTROSTATIC IMMOBILIZATION AT THE AIR-WATER-INTERFACE

The deposition of ordered multilayer Langmuir-Blodgett films of carbox ylic acid derivatized Q-state CdS nanoparticles through electrostatic interaction with octadecyl amine Langmuir monolayers is demonstrated i n this communication. The degree of nanoparticle incorporation into th e Langmuir monolayer can be controlled by varying the charge on the am ine molecules through the colloidal subphase pH. Pressure-area isother ms were used, to follow the adsorption of the Q-state colloidal CdS pa rticles at the amine surface while quartz crystal microgravimetry (QCM ), optical absorption spectroscopy and ellipsometry were used to chara cterize the multilayer LB films. The films were found to grow in the c lassical Y-type mode. Ellipsometry measurements indicated a bilayer th ickness of 8.2 nm which yields a fluster size of 3.2 nm, in reasonable agreement with a mean cluster size of similar to 3.5 nm determined fr om the position of the band edge obtained from optical absorption meas urements, Incorporation of clusters into inorganic matrices as outline d in the communication shows promise for the growth of superlattice st ructures mixed cluster systems, etc., which are not realizable by curr ently-used experimental methods. (C) 1998 Elsevier Science S.A.