Dynamic Multimodal Chemical Imaging of Biological, Environmental and Material Interfaces

The air - liquid, solid - liquid, and liquid - liquid interfaces have unique kinetics and thermodynamics, distinct from the bulk. However, major surface analytical techniques are mostly vacuum-based and direct applications involving volatile liquids are difficult. We developed a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable direct observations of the vacuum - liquid interface approximating the air - liquid and the solid - liquid interface using in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS), scanning electron microscopy (SEM), and a multitude of spectroscopy and microscopy tools. This presentation will showcase our latest results of 1) air - liquid interfaces in biology and microbiology (e.g., single cells, bacteria biofilms); 2) solid - liquid and liquid - liquid interfaces in novel materials (i.e., CO₂ capture solvents, emulsions); and 3) evolving energized solid - liquid interfaces using <i>in operando</i> imaging (i.e., redox reactions, lithium sulfur battery electrolyte). Our in situ multimodal chemical imaging capabilities open new directions and applications of biological, environmental, and material interfaces and show the potential of studying chemistry from the bottom up based on microfluidics and formulating engineering solutions extracted from molecular level understandings.