X-ray photoelectron spectroscopy system performs at industrially realistic pressures and temperatures

Industrial processes, such as energy production and energy storage, rely on catalyst materials to help protect the environment by minimizing the energy consumption. Scientists have extensively researched how molecules transform on surfaces using controlled experimental conditions at low pressures but have struggled to follow chemical transformations while reactions take place under realistic conditions.

Detecting emitted photoelectrons at pressures of several bars and realistic temperatures would allow researchers to study catalytic reactions under industrially relevant conditions.

Amann et al. developed an experimental technique, which probes catalytic reactions under more realistic conditions. They used a high-pressure x-ray photoelectron spectroscopy (XPS) system and developed the concept of a virtual cell, where gas flows onto the sample surface and creates a localized high-pressure pillow.

“By using a virtual cell, we can take advantage of several key features simultaneously. It allows for using grazing-incidence hard x-rays, creating only a local high pressure and controlling the sample-to-aperture distance with very high precision. All work together to increase the signal-to-noise ratio of our spectroscopic signal.” Peter Amann said.

Their instrument has the capability to perform XPS at pressures exceeding 1 bar and control temperatures of up to 500 degrees Celsius.

The authors developed the virtual cell approach for its open design, which allows for direct access of the interaction region with x-rays or optical microscopy while also decreasing the scattering probability through the gas. The virtual cell approach can be combined with other spectroscopic techniques.

The presented instrument is expected to give fundamental, new insights to industrially relevant catalytic reactions. Future research will push towards even higher pressures.

Source: “A high-pressure x-ray photoelectron spectroscopy instrument for studies of industrially relevant catalytic reactions at pressures of several bars,” by Peter Amann, David Degerman, Ming-Tao Lee, John D. Alexander, Mikhail Shipilin, Hsin-Yi Wang, Filippo Cavalca, Matthew Weston, Jörgen Gladh, Mikael Blom, Mikael Björkhage, Patrik Löfgren, Christoph Schlueter, Patrick Loemker, Katrin Ederer, Wolfgang Drube, Heshmat Noei, Johann Zehetner, Henrik Wentzel, John Åhlund, and Anders Nilsson, Review of Scientific Instruments (2019). The article can be accessed at https://doi.org/10.1063/1.5109321 .