We invented a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable direct observations of liquid surfaces, air-liquid, liquid-liquid, and solid-liquid interactions using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and a variety of spectroscopy and microscopy characterization techniques. In this talk, I will show three examples of how ToF-SIMS and in situ liquid SIMS are used in studying the air-liquid and liquid-liquid interfaces of importance in the environment. First, ToF-SIMS is applied to study if photochemistry plays a role in the photolysis of pyruvic acid in water. Depth profiling results coupled with spectral and multivariate analysis illustrate strong influence of the air-water interfacial photochemistry in pyruvic acid oxidation. Second, the effect of time on photochemical aging in glyoxal and hydrogen peroxide photochemical aging is studied using in situ liquid SIMS. Our results offer new insights into the evolution of the air-liquid interface and formation of aqueous secondary organic aerosol (aqSOA) over time. Third, the oil-in-water bilgewater emulsion is studied using in situ liquid SIMS. The evolving liquid-liquid interface is mapped showing hydrophobicity and hydrophilicity changes at the microscale.

<i>In situ</i> molecular imaging of the air-liquid and liquid-liquid interface in the environment

2019 Fall National Meeting

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In situ molecular imaging of the air-liquid and liquid-liquid interface in the environment