Christopher J Pursell    Professor    Physical Chemistry    phone: (210) 999-7381    FAX: (210) 999-7569    email: cpursell@trinity.edu    ** Teaching    ** Research    ** Vita    ** Family Pictures
	** Academic Leave to New Zealand

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Teaching Interests
    As the chemistry department's only physical chemist, I teach the year-long physical chemistry lecture courses (PChem 1 in the Fall - chemical kinetics and thermodynamics; PChem 2 in the Spring - quantum mechanics, symmetry, spectroscopy, and statistical thermodynamics) and the accompanying laboratory in the spring.  I also periodically teach an advanced topics course, an advanced laboratory, general chemistry and the general chemistry laboratory.
   Concerning teaching pedagogy, I have been developing new experiments for the physical chemistry laboratory and new approaches and lectures for the physical chemistry courses and the general chemistry courses.  I continue to develop new approaches of presenting chemical concepts in the classroom along with pedagogically sound experiments for both the physical chemistry laboratory and the introductory general chemistry laboratory.  For example, I reorganized the general chemistry laboratory course and rewrote the laboratory manual.

Research - Atmospheric Surface Chemistry; Guest-Host Binding; Fuel Film Evaporation

1.         Atmospheric Surface Chemistry - Our research group has been examining chemical reactions in ice and on ice surfaces.  The motivation is to help develop a better understanding of the heterogeneous reactions that occur in the atmosphere and that lead to the seasonal loss of ozone over the poles.  In the laboratory we simulate the surface of these atmospheric ice particles, known as Polar Stratospheric Clouds or PSCs, using thin films of pure water ice and mixtures of water with nitric acid.  The interaction of reactive species with the ice surface is monitored using infrared transmission spectroscopy.  The overall goal is to provide detailed experimental information that will help us better understand the chemical reactivity of the ice surface and ice-like surfaces.  Results from these studies will lead to a better understanding of the heterogeneous chemistry that occurs on atmospheric ice particles.  An example of one of our recent studies involved examining the isotopic exchange of D₂O on H₂O ice.  Using infrared spectroscopy we were able to monitor the formation of HOD in time and get kinetics information.

Very recently we have extended our studies of ice and have begun to study the physical and chemical properties of the molecular cousins of ice, namely solid ammonia and solid hydrogen sulfide.  These studies involve using infrared spectroscopy, very low temperatures (10-180 K), and a vacuum environment.  We have already discovered some very fascinating spectroscopic differences between these “cousins” and ice.  We hope to now study chemical reactions of these solids in order to compare and contrast their chemical and physical behavior.

2.         Guest-Host Binding - We have recently begun to study the binding of iodine species with cyclodextrine.  This is called guest-host chemistry.  The cyclodextrine is a large, basket-shaped molecule made from sugar molecules.  The iodine species (I^-, I₂ and I₃^-) fit inside the cyclodextrine and form a fairly stable complex.  This is an equilibrium process and we are interested in measuring the equilibrium constant (called the binding constant) and in determining the heat for this process.  Besides using UV-Vis spectroscopy to study the binding, we are interested in using a new instrument in the department that can measure the heat associated with the binding processes.

3.         Fuel Film Evaporation - This is a joint project with Dr. Kelly-Zion in the Engineering Science department.  Thin films of fuel can be deposited in the interior of an automobile engines, especially under cold, initial operation.  These fuel films lead to reduced performance and increased pollution.  We are studying the evaporation process of model films that represent these automobile fuel films.  These studies include (1) using infrared spectroscopy to watch the individual components evaporate, (2) using light interference from a laser to measure the film thickness during evaporation, and (3) using laser light interaction with the film’s surface and capturing the image with a digital camera (this gives information about turbulence).

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** This webpage is maintained by Chris Pursell.  Last modified January 22, 2006.