The PEAXIS beamline

New research infrastructure for catalytic materials and conversion of heat to electrical energy

What can you do with the new beamline?

PEAXIS facilitates studying the electronic structure of new materials by means of spectroscopy with photons. Catalytic materials as well as materials for conversion of heat to electrical energy are the main focus.

What is new about it?

The construction of PEAXIS at BESSY II makes a beamline available for the first time that enables the scattering angle in high-resolution spectroscopy to be continuously varied. The sample environment available is new, covering a wide temperature range over which material samples can be studied.

What is the goal?

The goal of the research work on thermoelectric materials is to substantially increase the efficiency of the materials for converting thermal energy to electrical energy by thoroughly understanding the transport processes of electrons and heat. This technology will be employed for production of electrical energy in the future. For catalytic materials, it is important to study the interaction of materials and light under realistic conditions of use. In this way, solar fuels can be used in the future for clean energy production.

PEAXIS Spektrometer

Layout of the new PEAXIS spectrometer that was built by the PREVAC company in Rogów, Poland. The sample chamber (green) can accept various manipulators (red) that have been designed for RIXS experiments on either solids or liquids. In addition, the electron analyser (violet) attached to the sample chamber permits photoelectron spectroscopy. The grating chamber (dark blue) can be positioned along the RIXS analyser arm (light blue), and different distances selected between the sample and detector (orange). The analyser arm can be continuously swept through an angle of +/ – 55°.

About the PEAXIS project

The new photo-electron analysis and X-ray inelastic spectroscopy instrument platform (PEAXIS) at BESSY II makes available resonant inelastic X-ray scattering (RIXS) and angle-resolved X-ray photo-electron spectroscopy (PES) methods for energy materials research on liquids, solid samples, and at liquid/solid boundaries in a single instrument [1]. The RIXS setup combines high energy resolution with a wide range of momentum transfers. A continuous range of momentum transfers is made possible thanks to the continuous sweep of the analyser arm about the sample. Two precision spherical gratings (2,400 lines/mm) with variable line separations allow measurement of photon energies over a range of 200–1,200 eV.

Two manipulators that facilitate RIXS and angle-resolved PES over temperature ranges of 20–300 K or 300–1,000 K are available for studying the electronic structure of single-crystal samples. Experiments are planned on solid samples to explore in particular the electronic configuration and electron transport across interfaces of thermoelectric nanomaterials as well as electrocatalytic and photocatalytic materials. RIXS can resolve specific elements in the local electronic structure, and provide wave-vector information on electron/photon coupling and thus on the dynamics in energy materials. The combination of angle-resolved electron spectroscopy and wave-vector-resolved photon spectroscopy permits study of the electronic configuration in the interior of bulk samples as well as at interfaces.

Changes in the electronic configuration of catalytic materials in solution can be empirically followed with PEAXIS using microfluidic cells that facilitate study of a wide range of different materials – from simple transition-metal complexes to nanomaterials containing organic or inorganic photoabsorbers.

Moreover, utilisation of photonic and electronic microfluidic cells in the sample chamber of PEAXIS permits advanced development of technologies mirroring actual applications. To increase the efficiency of photocatalytic and electrocatalytic water splitting, it is necessary for example to study local chemical reactions at the interfaces. To accomplish this, transient molecular states over different timescales must be identified and followed.

The project is being funded by the HZB and the German Federal Ministry of Education and Research (BMBF) under BMBF promotional reference 05K13KE4 (subject area physics, Freie Universität Berlin – Prof. E. F. Aziz)


[1] Klaus Lieutenant, Tommy Hofmann, Christian Schulz, Mikhail V. Yablonskikh, Klaus Habicht, Emad F. Aziz, “Design concept of the high-resolution end-station PEAXIS at BESSY II: Wide-Q-range RIXS and XPS measurements on solids, solutions, and interfaces”, J. Electron Spectrosc. Relat. Phenom. 201 54-65 (2016).

Project Manager, Thermoelectrics: Klaus Habicht (Department of Methods for Characterisation of Transport Phenomena in Energy Materials)

Project staff: Christian Schulz, Jie Xiao, Klaus Lieutenant, Tommy Hofmann