GAS JET INJECTION OF CLUSTERS INTO LIQUIDS

IN THIS PROJECT WE WILL DEVELOP A NOVEL TECHNIQUE, GAS JET INJECTION (GJI), FOR GENERATING NANOMETER SIZED CLUSTERSIN COLLOIDAL FORM. GJI EMPLOYS NEAR SONIC GAS JETS TO INJECT ATOMS AND MOLECULES INTO LIQUIDS, SUCH AS WATER, UNDER THEIR OWN VAPOR PRESSURE. IT IS A GENERAL TECHNIQUE THAT CAN BE USED IN PRINCIPLE TO MAKE COLLOIDS OF METALS, SEMICONDUCTORS, OXIDES, AND ORGANIC SPECIES. IT IS A PHYSICAL METHOD THAT IS EASILY IMPLEMENTED WITH SIMPLE "LOW VACUUM" EQUIPMENT, AND CAN READILY BE SCALED UP AND USED IN A CONTINUOUS MODE. WE HAVE USED GJI TO MAKE METAL SOLS WITH SMALL (NANOMETER) SIZE AND NARROW DISTRIBUTION IN WATER, GLYCEROL, AND EPOXY RESIN, BUT LITTLE IS KNOWN ABOUT ITS BASIC PHYSICS. WE PROPOSE TO INVESTIGATE THE MECHANISM OF COLLOID NUCLEATION IN GJI, DEMONSTRATE THAT IT CAN BE USED TO MAKE NON-METALLIC COLLOIDS IN THE NANOMETER SIZE RANGE, AND RESTRUCTURE OUR GJI SYSTEM FOR LARGER SCALE,HIGH RATE, CONTINUOUS OPERATION. ULTRAFINE SEMICONDUCTOR COLLOIDS ARE OF INTEREST BECAUSE THEIR PARTICLE SIZE INFLUENCES ELECTRONIC, OPTICAL, AND PHOTOCATALYTIC PROPERTIES. NANOMETER RANGE COLLOIDS ARE POTENTIALLY USEFUL AS STARTING ELEMENTS FOR "NANOPHASE" SYNTHESIS OF MATERIALS WITH ULTRAFINE GRAIN SIZE AND A HIGH FRACTION OF ATOMS AT GRAIN BOUNDAIRES. THESE AGGREGATED MATERIALS EXHIBIT NOVEL PROPERTIES AND ARE LIKELY TO FIND FUTURE APPLICATIONS, BUT INNOVATIVE APPROACHES TO PRODUCING THE PRECURSOR COLLOIDS ARE NEEDED. OUR PROPOSED RESEARCH IS INTENDED TO REFINE AND DEVELOP GJI FOR THAT PURPOSE.