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Recent approaches for bridging the pressure gap in photoelectron microspectroscopy



Andrei A. Kolmakov, Luca Gregoratti, Maya Kiskinova, Sebastian Gunther


Ambient pressure photoelectron spectroscopy (APPES) and microscopy are at the frontier of modern chemical analysis at liquid-gas, solid-liquid and solid-gas interfaces, bridging science and engineering of functional materials. Complementing the current state-of-the art of the instruments, we survey in this short review several alternative APPES approaches, developed recently in the scan-ning photoelectron microscope (SPEM) at Elettra laboratory. In particular, we report on experimental set-ups for dynamic near-ambient pressure environment, using pulsed gas injection in the vicinity of the samples or reaction cells with very small apertures, allowing for experiments without introducing additional differential pumping stages. The major part of the review is dedicated to the construction and performance of novel environmental cells using ultrathin electron transparent but molecularly impermeable membranes to isolate the gas or liquid ambient from the electron detector operating in UHV. We demonstrate that two dimensional materials, such as graphene and derivatives, are mechanically robust to withstand atmospheric - UHV pressure difference and are sufficiently transparent for the photoelectrons emitted from samples immersed in the liquid or gaseous media, which opens unique opportunities for APPES using X-ray in a wide energy range. The re-ported representative results illustrate the potential of these ‘ambient-pressure’ approaches. Combined with the lateral resolution of SPEM, they can overcome the pressure gap challenges and ad-dress the evolution of chemical composition and electronic structure at surface and interfaces under realistic operation conditions with unprecedented lateral and spectral resolution.
Topics in Catalysis


ambient pressure XPS, graphene membranes, environmental cell, microscopy


Kolmakov, A. , Gregoratti, L. , Kiskinova, M. and Gunther, S. (2016), Recent approaches for bridging the pressure gap in photoelectron microspectroscopy, Topics in Catalysis, [online], (Accessed June 20, 2024)


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Created January 29, 2016, Updated November 10, 2018