AER/I Chemistry doctoral final defense with Cameron Naylor

About the event

Presenter: Cameron Naylor
Group: Clowers
Title: High resolution ion mobility spectrometry in complex environments

Abstract:  If organic compounds are going to be detected and quantified with high fidelity in the soil and atmosphere in the solar system, increased levels of resolution for portable instruments are needed that can withstand harsh conditions. Since ion mobility spectrometry (IMS) is one of the most widely used portable analytical techniques on Earth that is compatible with a wide range of operating conditions, IMS serves as an excellent candidate requiring little to no sample preparation and capable of utilizing purified atmospheric gases as the buffering medium. The benefit of IMS as a technique allows the composition of trace organics in a planet’s soil or atmosphere to be tested on the time scale of milliseconds over a range of operating conditions. However, IMS theory needs to be expanded to account for temperatures, gases, and pressures on other planets.

Contained within this dissertation is the theoretical and experimental foundations IMS that requires direct attention prior to deployment for extraterrestrial missions. Towards this goal a suite of linked experimental endeavors is introduced including accurate calibration techniques for trapped ion mobility spectrometry (TIMS) using reference mobilities from a drift tube IMS (DTIMS). Secondly, the calibration practice developed in the first chapter is extended to analyze “thermometer ions” on the TIMS to establish an effective temperature within the reduced pressure environment without a thermocouple. Subsequently, Blanc’s Law is applied to establish its viability for predicting mobilities of polyatomic ions in complex gas mixtures within 1% error. Blanc’s Law is further applied to alternate conditions such as those contained in the TIMS and at elevated temperatures within a DTIMS. Most importantly, throughout all these conditions, Blanc’s Law applies to polyatomic ions within experimental error. Additionally, theoretical considerations of this body of experiments are addressed with regards to how ion-neutral interactions should be considered, especially for modeling purposes, by the IMS community. These experiments establish the groundwork for measuring accurate ion mobilities and providing an accurate means to predict mobilities in complex environments. Using the foundation in this dissertation, IMS systems could potentially be exported to other stellar bodies and aid efforts to characterize extraterrestrial environments.

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