Enabling photoemission electron microscopy in liquids via graphene-capped microchannel arrays

Abstract: Photoelectron emission microscopy PEEM is a powerful tool to spectroscopically image dynamic surface processes at the nanoscale but is traditionally limited to ultra high or moderate vacuum conditions. Here, we develop a novel grapheme capped multichannel array sample platform that extends the capabilities of photoelectron spectromicroscopy to routine liquid and atmospheric pressure studies with standard PEEM setups. Using this platform, we show that graphene has only a minor influence on the electronic structure of water in the first few layers and thus will allow for the examination of minimally perturbed aqueous phase interfacial dynamics. Analogous to microarray screening technology in biomedical research, our platform is highly suitable for applications in tandem with large-scale data mining, pattern recognition, and combinatorial methods for spectro temporal and spatiotemporal analyses at solid liquid interfaces. Using Bayesian linear unmixing algorithm, we were able to discriminate between different X-ray induced water radiolysis scenarios and observe a metastable wetting intermediate water layer during the late stages of bubble formationformation