COLL 494 |
| Pedro Gozalez, Raymond Sung, and Subra Muralidharan. Department of Chemistry, Western Michigan University, Kalamazoo, MI 49008 |
| Mn doped Zinc sulphide quantum dots of 5 nm diameters were synthesized in aqueous media using sodium polyphosphate as stabilizer. These quantum dots show a strong emission line at 590 nm due to the 4T1-6A1 transition characteristic of Mn occupying Zn positions in the lattice. The reaction of neutral L-cysteine with the ZnS:Mn(II) nanoparticles strongly enhances the intensity of the 590 nm emission line. The enhancement of the signal intensity depends on the L-cysteine concentration and follows a Langmuir isotherm behavior. The stability constant for the ZnS:Mn(II)-Cysteine system was experimentally calculated from the curve q vs 1/[Cys] showing a value of 1.81x104 M-1 at pH 7.0 . The system shows a strong increase in the reaction rate and in the final intensity of the 590 nm emission line upon UV irradiation. Examination of the EPR spectra of the Mn(II) doped ZnS quantum dots indicates that the Mn atoms are mostly inside the nanocrystal and that L-cysteine essentially interacts with Zn atoms on the surface of the nanoparticle. The fundamental aspects of the interactions of the quantum dots with L-cysteine will be discussed. |
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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 |