Laboratory Based Hard X-ray Photoelectron Spectroscopy

Hard X-ray photoelectron spectroscopy (HAXPES) is generally used to study core topics in condensed matter physics. However with a worldwide increase in the number of HAXPES focused endstations, many other interest groups now recognize its broad appeal.
In a HAXPES experiment 2-10 keV X-rays are used to excite photoelectrons to study the chemical environment and electronic structure of materials non-destructively. In contrast to standard XPS, HAXPES is more sensitive to what is beneath the surface. This makes it an ideal technique for studying structured samples that cannot be analyzed using traditional XPS. Bulk sensitivity means that realistic samples can be investigated without the need for surface preparation. Unfortunately, there are very few existing HAXPES systems. Most are predominantly located at synchrotrons, as the photoionization cross sections at high energies is small and necessitates large X-ray intensities.
This work shows a new laboratory based HAXPES instrument capable of delivering monochromated 9.25 keV X-rays in a focused 30x45 μm² X-ray spot with energy resolution <0.5 eV. Systematic reference measurements demonstrate the system’s capability. Application based results from various fields, including measurements of energy related materials, are also presented.