COLL 495 |
| Curtis Deer and Subra Muralidharan. Department of Chemistry, Western Michigan University, Kalamazoo, MI 49008 |
| Quantum dots are semiconductor nanoparticles whose band gaps are size dependent and they have uv absorption around 320 nm characteristic of this band gap where valence band electron is excited into the conduction band. The corresponding emission band is 400-430 nm depending on the size of the particles. The introduction of dopants such as transition and lanthanide metal ions results in a new emission band at significantly longer wavelengths and higher quantum yield compared to the emission due to the undoped quantum dots. These ions depending on their concentration can either be present in the bulk of the lattice, on the surface of the nanoparticle or both. Doping lanthanide metal ions is interesting to determine their influence on the long wavelength emission due to the similarities in their sizes and electronic structures. Lanthanide doped ZnS quantum dots have been synthesized in the aqueous phase in the presence of polyphosphate and Brij 35 surfactant as stabilizers and in methanol-water mixtures in the absence of any stabilizers. Their absorption and emission spectra have been investigated in detail. Their size distribution has been studied by TEM, lattice structure by XRD, and electronic structure by XPS. The interaction of the lanthanide doped quantum dots with organic molecules and inorganic ions have also been investigated and these studies will be presented. |
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Nanoscience and Nanotechnology
8:30 AM-11:45 AM, Thursday, April 1, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |