NANOSCOPIC ANALYSIS OF GAS ADSORPTION ON IONIC LIQUID DROPLETS

With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professor Terefe Habteyes at the University of New Mexico is investigating how gases interact with the surfaces of ionic liquid droplets (ILDs) at the nanoscale. Ionic liquids are special types of salts that are liquid at room temperature and have attracted attention for their ability to capture gases without evaporating. However, understanding how gas molecules behave at the surface of ILDs is particularly challenging due to the complex and varied nature of their interfaces at the nanoscale. Professor Habteyes and his students will tackle this challenge by using near-field optical methods to resolve chemical heterogeneity across individual droplets and understand how the interaction of gas molecules with ILDs can be manipulated and optimized. Their discoveries could provide a fundamental understanding of how ionic liquids adsorb gases, which is key to designing more efficient materials for gas separation and catalysis. In addition to advancing science, the project offers hands-on research opportunities for graduate and undergraduate students, helping to build a skilled scientific workforce through collaborations with the Air Force Research Laboratory and access to advanced nanotechnology facilities. This project aims to investigate the molecular-scale mechanisms of gas adsorption on ILDs supported on solid substrates, with a particular focus on understanding interfacial heterogeneity of gas adsorption. The research employs nano-FTIR (Fourier transform infrared) spectroscopy to identify chemical species based on the vibrational resonance of chemical bonds, and scattering-type scanning near-field optical microscopy to map the spatial distribution of the chemical species with about 10 nm spatial resolution. These near-field optical techniques will be used to examine the stability and dynamic response of ILDs under external stimuli, such as thermal or gas exposure. By integrating the near-field measurements with atomic force microscopy, the project will enable real-space, spatio-spectral mapping of adsorption events at nanometer resolution. This approach provides the ability to identify and map chemical heterogeneity across individual ILDs, allowing for the resolution of localized interactions and adsorbate-induced changes in composition or structure. The research will provide mechanistic insights into how droplet size, morphology, and molecular structure influence gas capture efficiency and selectivity. The broader goal is to establish design principles for IL-based adsorbents by correlating nanoscopic interfacial phenomena with macroscopic gas sorption behavior, potentially informing applications in catalysis, gas separation, and the development of sustainable materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.