Near ambient pressure photoelectron spectro-microscopy: from gas-solid interface to operando devices

Near Ambient Pressure Scanning Photoelectron Microscopy adds to the widely used photoemission spectroscopy and its chemically selective capability two key features: (i) the possibility to chemically analyse samples in a more realistic environmental, gas pressure condition, and (ii) the capability to investigate a system at the relevant spatial scale. To achieve these goals the approach developed at the ESCA Microscopy beamline at the Elettra Synchrotron facility combines the submicron lateral resolution of a Scanning Photoelectron Microscope with a custom designed Near Ambient Pressure Cell where a gas pressure up to 0.1 mbar is confined inside it around the sample. In this manuscript a review of experiments performed with this unique setup will be presented to illustrate its potentiality in both fundamental and applicative research such as the oxidation reactivity and gas sensitivity of metal oxides and semiconductors. In particular the capability to do operando experiment with this setup opens the possibility to perform investigations with active devices to properly address the real nature of the studied systems, because it can yield to more conclusive results when microscopy and spectroscopy are simultaneously combined in a single technique.