ANYL 191 |
| Trace explosive detection is a major technological challenge. Selectivity and sensitivity are major issues in sensing trace amounts of explosive material. We report on femtosecond laser off-resonance fluorescence measurements of quantum dots-TNT assemblies in solution. The fluorescence emission of ZnS protected CdS quantum dots mixed with trace amounts of TNT is found to depend on the amount of TNT and the size of the QD. In QD that are between 2 and 5 nm in diameter, both red and blue shifts are observed in the fluorescence emission of the QD. A strong quenching of the fluorescence emission accompanies the observed shifts. The results are explained in terms of (1) a charge transfer mechanism based on charge injection from the photoexcited electrons in the TNT into the conduction band of the nanoscaled semiconductor and (2) introduction of new trap states localized in the TNT. The consequences of the experimental results in future developments of sensors for TNT detection are discussed.
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General Papers
7:00 PM-9:00 PM, Sunday, 28 August 2005 Washington DC Convention Center -- Hall A, Poster
Sci-Mix
Division of Analytical Chemistry |