@article{Adsorption:2177,
      recid = {2177},
      author = {Thompson, Rebecca},
      title = {Adsorption, Diffusion, and Reaction in Condensed Films:  Nerve Agent Simulants, Extraterrestrial Ices, and Olefin  Oxidation},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2020-03},
      pages = {232},
      abstract = {This thesis describes a diverse set of experiments that  probe the interfacial dynamics of complex molecular thin  films. Topics include the oxidative and thermal destruction  of chemical warfare agents, sticking of small molecules on  and in extraterrestrial ices, heterogeneous catalysis in a  high-pressure reactor, and oxidation of an important  industrial alkene. While the systems of study differ  dramatically, all projects focus on uncovering the precise  mechanisms of reactivity in condensed films in which  diffusion, stable reactive intermediates, and film  structure play a crucial role in the observed chemistry. In  the oxidative destruction of chemical warfare agent  simulants, we find that despite rapid initial reactivity,  the build up of a dense product overlayer on the simulant  film hinders full destruction of thicker films. Oxygen  plays a similarly vital role in the destruction of these  compounds under high-temperature, atmospheric pressure  conditions.

Even initial adsorption can be critically  influenced by film structure, as is the case for methane  adsorption on water ice. Our work on this system, which has  direct relevance to astrophysical environments,  demonstrates that high energy methane sticks more readily  to porous amorphous ice films than to either crystalline or  non-porous amorphous films, likely due to efficient energy  accommodation by the pore structure. Even when a reaction  isn’t expected, the right high-temperature and  high-pressure system can be ripe for heterogenous  chemistry. In this case, a supersonic molecular beam nozzle  acts as a highly efficient reactor for the production of CO  and H<sub>2</sub>O from a mixture of CO<sub>2</sub> and  H<sub>2</sub>. Finally, we find that in the oxidation of  condensed propene (an important combustion intermediate  species), propene film structure can have a profound effect  on the diffusion and subsequent reactivity of oxygen. In  addition to highlighting the applicability and  effectiveness of time-resolved, surface-sensitive  spectroscopic techniques, this work clearly demonstrates  the many factors that influence complex reactivity in  condensed phases. Product distributions and reaction  barriers often differ dramatically due to many-body  interactions in the film. Even when barriers are low,  contact between reactive species may be significantly  hindered by low adsorption probabilities, diffusion  constraints, and film morphology.},
      url = {http://knowledge.uchicago.edu/record/2177},
      doi = {https://doi.org/10.6082/uchicago.2177},
}