SYNTHESIS OF SIZE-MONODISPERSE CDS NANOCRYSTALS USING PHOSPHATIDYLCHOLINE VESICLES AS TRUE REACTION COMPARTMENTS

Phosphatidylcholine vesicles provide reaction compartments for synthes is of size-quantized CdS nanocrystals of dimension predicted to within 2.5 Angstrom on the basis of initial encapsulated CdCl2 concentration and vesicle diameter. Vesicle formation by detergent dialysis of phos phatidylcholine/hexylglucoside mixed micelles yields highly monodisper se lipid capsules within which monodisperse CdS nanoparticles are prec ipitated with sulfide. Size-quantized CdS nanocrystals, with diameters ranging from 20 to 60 Angstrom, have been produced with typical stand ard deviations about the mean diameter of +/-8%, as measured by transm ission electron microscopy. Spectrophotometric and photoluminescence s pectra are consistent with highly crystalline, monodisperse particles with few core or surface defects. Measured exciton energies show excel lent agreement with data in the literature. The empirical pseudopotent ial model presented by Krishna and Friesner for a cubic CdS lattice, c orrecting for experimentally measured lattice contractions, best fits the exciton energy versus particle diameter data.