Title page for ETD etd-11172006-101005


Type of Document Dissertation
Author Gordon, Wesley Odell
Author's Email Address wegordon@vt.edu
URN etd-11172006-101005
Title Metal Oxide Nanoparticles: Optical Properties and Interaction with Chemical Warfare Agent Simulants
Degree PhD
Department Chemistry
Advisory Committee
Advisor Name Title
Tissue, Brian M. Committee Chair
Anderson, Mark R. Committee Member
Brewer, Karen J. Committee Member
Morris, John R. Committee Member
Yee, Gordon T. Committee Member
Keywords
  • phosphor
  • lanthanide
  • energy transfer
  • size-dependent reactivity
  • yttrium oxide
  • dimethyl methylphosphonate
Date of Defense 2006-11-06
Availability unrestricted
Abstract
Materials with length scales in the nanometer regime demonstrate properties that are remarkably different from analogous bulk matter. As a result, researchers are striving to catalog the changes in properties that occur with decreasing size, and more importantly, understand the reason behind novel nanomaterial properties. By learning the true nature of nanomaterials, scientists and engineers can design better materials for a variety of applications. Inert gas-phase condensation synthesis of metal oxide nanoparticles was used to develop materials to explore the optical and chemical properties of metal oxide nanoparticles.

One potential application for nanomaterials is use in optical applications. The possibility of interparticle energy transfer was investigated for lanthanide-doped yttrium oxide nanoparticles using laser spectroscopy. Experimental evidence collected with this study indicates that interparticle, lanthanide-mediated energy transfer may have been observed. In addition, lanthanide-doped gadolinium oxide nanoparticles were synthesized and investigated with optical spectroscopy to identify the best potential candidates for bioanalytical applications of this material. The influence of particle annealing and dopant concentration were also studied.

Nanoparticle film structure was investigated with scanning electron microscopy. Two different film structures composed of oxide nanoparticles were found to grow under different synthesis conditions. The film structure was found to be determined by the degree of particle aggregation in the gas phase during synthesis. Aggregation of the particles was found to be controlled by a combination of gas pressure and properties.

Chemical properties of metal oxide nanoparticles also are very important. Reflection-absorption Infrared Spectroscopy and vacuum surface analytical techniques were used to explore the chemistry of the chemical warfare agent dimethyl methylphosphonate (DMMP) on yttrium oxide as well as other metal oxide nanoparticles. DMMP was found to dissociate at room temperature on several types of metal oxide nanoparticles. Hydroxyl groups were found to be critical for the adsorption of DMMP onto the particles. Finally, the reactivity of the nanoparticles was found to increase with decreasing particle size. This was attributed to a relative increase in the number of high-energy surface defects for the smaller particles.

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