Date of Award
Spring 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Johnson, Mark
Abstract
Sea Spray Aerosols (SSA) generated from ocean wave breaking constitute one the largest sources atmospheric particulate matter, and can exhibit enormous diversity in their chemical composition. Heterogenous reactions occurring at the air-water interface of these SSA particles are thought to play a key role in the regulation of gas-phase oxidants and greenhouse gases in the troposphere and thus have broad implications for global climate. Unfortunately, the underlying chemical physics associated with interfacial reactivity is poorly understood and large uncertainties in the mechanisms, relative product yields, and kinetics of the processes occurring on SSA surfaces remain. In this dissertation, SSA reactivity is characterized at the molecular level by interrogating the products of collisions between the gaseous pollutants dinitrogen pentoxide (N2O5) and hypochlorous acid (HOCl) with charged water cluster model systems. This is accomplished by implementing a new custom-designed dual-ion trap mass spectrometer with additional temperature control and mass-selective capabilities. This instrument is first used to investigate the chemical speciation of N2O5 reactive uptake on I–‧(D2O)n clusters as a function of cluster size and kinetic energy. The instrument is then integrated with infrared and ultraviolet cryogenic ion spectroscopy interfaces to enable structural characterization of the binary interactions between halides (X− = Cl−, Br−, I−) and HOCl formed by HOCl uptake on X−∙(H2O)n clusters. Analysis of the cold vibrational signatures and electronic structures of the resulting X−⋅HOCl ion-molecule complexes reveals key insights into the influences of hydrogen and halogen bonding motifs on HOCl reactivity. Finally, this approach is applied to more complex organic systems by considering the oxidation of methionine (Met) by HOCl to yield methionine sulfoxide (MetO). Collisions of deprotonated methionine water clusters, Met–‧(H2O)n, with HOCl are found to efficiently generate the expected MetO– oxidation product as well as a reaction intermediate identified as the MetO–∙HCl exit-channel complex. Calculated stationary points along the reactive potential energy surface of Met oxidation support a mechanism based on a cyclic S∙∙∙O∙∙∙H motif.
Recommended Citation
Stropoli, Santino James, "Characterizing Reactive Uptake at the Air-Water Interface of Sea Spray Aerosols using Cryogenic Ion Spectroscopy" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1092.
https://elischolar.library.yale.edu/gsas_dissertations/1092
