Title page for ETD etd-10092012-194138


Type of Document Master's Thesis
Author Wagner, Alec Thomas
Author's Email Address atw136@vt.edu
URN etd-10092012-194138
Title Fundamental Studies of Two Important Atmospheric Oxidants, Ozone and Hydroxyl Radical, Reacting with Model Organic Surfaces
Degree Master of Science
Department Chemistry
Advisory Committee
Advisor Name Title
Morris, John R. Committee Chair
Esker, Alan R. Committee Member
Tissue, Brian M. Committee Member
Keywords
  • Rotational State Selection
  • Electrostatic Hexapole
  • Ozone
  • Hydroxyl Radical
  • Pentacene
  • Linear Stark Effect
Date of Defense 2012-09-26
Availability restricted
Abstract
Heterogeneous reactions between gas-phase oxidants and particulate-phase organic compounds impact many important atmospheric chemical processes. For example, little is known about the reaction dynamics of gaseous oxidants with organic compounds found in the atmosphere. The first step of the reaction between gaseous ozone and solid pentacene was investigated using Reflection Absorption Infrared Spectroscopy (RAIRS). Ozone was found to add to pentacene non-selectively and form a range of products after heavy ozone exposure. The rate limiting step had an activation energy of 17 kJ/mol, which is consistent with the findings of previous ozone oxidation studies for the cleavage of a carbon-carbon double bond. Unfortunately the products could not be used to distinguish between probable reaction mechanisms.

Hydroxyl radicals (•OH) play a major role processing atmospheric hydrocarbons. Due to their short lifetimes, not much is known about the dynamics of the first steps of •OH reactions. To investigate these reactions, a rotational state-selector was constructed to filter a molecular beam of •OH for reaction dynamics investigations with organic surfaces. The rotational state-selector was designed to leverage the linear Stark effect to pass only suitable molecules in a particular rotational state and block the flow of any other atoms, molecules and ions in a molecular beam. The state-selector was validated and used to positively deflect molecular beams of methyl iodide and D2O via the linear Stark effect. Future studies with the rotational state-selector will investigate the initial steps of •OH reactions with solid organic compounds.

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