COLL 450 |
| Sorelys Nieto1, Alberto Santana1, Samuel P. Hernandez1, Richard T. Lareau2, R. Thomas Chamberlain2, and Miguel E. Castro1. (1) Department of Chemistry, The University of Puerto Rico at Mayaguez, Chemical Imaging Center and Center for Chemical Sensor Development, Mayaguez, PR 00681, Mayaguez, PR 00681, (2) U.S. Department of Transportation, Transportation Security Administration, Transportation Security Research and Development Division, William J. Hughes Technical Center, Bldg. 315, Atlantic City, NJ 08405 |
| Detection of nitro organics is an important objective with a broad range of implications, from homeland security to the detection of nitro-based explosive residues in crime scences. Small and lightweight and field deployable systems that can be used for explosive detection systems can be developed with new and emerging nanotechnologies. In this presentation, we will present results on the use of fluorescent nanoparticles for the selective detection of trace amounts of TNT, a powerful explosive. Core shell protected CdSe quantum dots, excited (off-resonance) with a femto second laser pulse, exhibit a decrease in fluorescence signal intensity and shift in emission wavelength upon addition of solutions containing traces of TNT. The direction of the shift is sensitive to quantum dot size and amount of TNT adsorbed on the quatum dot surface. The largest shifts are observed when the femtosecond laser system is tuned to wavelenghts near the excitation edge of TNT optical absortpion. The surface chemistry that takes place on the nanoparticle is interrogated with a battery of surface analytical techniques that includes X-ray photoemission spectroscopy, near field optical microscopy, atomic force microscopy and Fourier transform infrared microscopy. A charge transfer process involving the injection of photoexcited electrons from the TNT into the conduction band of the quantum dots is proposed to account for the effect of TNT in the fluorescence emission of the quantum dots. The possibility of using quantum dots for trace explosive detection in a number of environments will be discussed. 1. Partial financial support from the Federal Aviation Administration (FAA), grant number 99-G-029 and the National Science Foundation, (award number 0304348), are gratefully acknowledged. |
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Nanoscience and Nanotechnology
2:00 PM-5:15 PM, Wednesday, March 31, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |