Photoelectron spectroscopy of wet and gaseous samples through graphene membranes

This report proposes an alternative ambient pressure approach that can be applied to a broad class of samples and be implemented in conventional PES instruments. It uses ultrathin electron transparent but molecular impermeable membranes to isolate the high pressure sample environment from the high vacuum PES detection system.
Kraus J, Vol. 6 - 23, pp. 14394-14403 (2014).

A novel APPES approach using graphene as an electron-, X-ray-, and optically transparent window separating the UHV analyzer chamber from the sample environment that allows for acquiring photoelectron spectra from fully hydrated interfaces has been developed and tested. Photoelectron spectroscopy (PES) and microscopy are highly important for exploring morphologically and chemically complex liquid–gas, solid–liquid and solid–gas interfaces under realistic conditions, but the very small electron mean free path inside dense media imposes serious experimental challenges. Currently, near ambient pressure PES is conducted using dexterously designed electron energy analyzers coupled with differentially pumped electron lenses which make it possible to conduct PES measurementsat a few hPa. In this work it has

been demonstrated that the separating graphene membrane windows are both mechanically robust and sufficiently transparent for electrons in a wide energy range to allow soft X-ray PES of liquid and gaseous water. The performed proof-of-principle experiments confirm the possibility to probe vacuum-incompatible toxic or reactive samples placed inside such hermetic, gas flow or fluidic environmental cells.

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Photoelectron spectroscopy of wet and gaseous samples through graphene membranes Kraus J, Reichelt R, Gunther S, Gregoratti L, Amati M, Kiskinova M, Yulaev A, Vlassiouk I, Kolmakov A, Vol. 6 - 23, pp. 14394-14403 (2014)
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