Understanding Differential Chemical Activities of Eutectic Gallium Indium (eGaIn) Thin Films with Fluorinated Analytes using Raman Spectroscopy
Year: 2026
Type: preprint
Abstract: Gallium oxide (Ga2O3) forms on the surface of eutectic gallium indium (eGaIn) alloy in air; In the presence of water, it transforms to gallium oxide monohydroxide, GaO(OH). During such transformation, it is challenging to differentiate the activities of the oxides while adsorbing solutes from the solvent. Herein, we address this challenge by investigating the temporal evolution of eGaIn thin films during adsorption of dilute organofluorines in water. We identify five hours as the stability threshold to obtain a water-modified thin film. Leveraging both fresh and five-hour-modified films in parallel, we distinguish water-specific changes and differentiate the signals uniquely caused by fluorinated analytes. The modified GaO(OH) interface demonstrates increased hydrophilicity for microdroplet studies and structural stability under high-energy (20 kV) electron beam irradiation. We leverage Frontier Molecular Orbital (FMO) theory to predict that the GaO(OH) surface is also a reactive catalytic interface. In the presence of the GaO(OH) surface and UVA irradiation, short-chain (HFBA) and long-chain (PFOA) fluorinated compounds exhibited altered interfacial activity. We leveraged Raman spectroscopy throughout our study to differentiate the in situ activities of Ga2O3 and GaO(OH). Our investigations will be useful for differentiating fresh and modified oxide dynamics during in situ interfacial studies or wet chemical measurements.
Source: ChemRxiv
Institution: University of Nevada, Reno
Language: English
Subfield: Surfaces, Coatings and Films
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213467110