Research

The Seidler group had two main research thrusts. First, we investigate the physics of environmentally- and industrially-relevant materials, with a strong emphasis on advanced x-ray techniques. This includes developing and applying new instruments and techniques for advanced x-ray spectroscopy in the laboratory setting and a wide range of major facilities. Second, again using x-ray methods, we create and study high-energy density plasma systems, such as by illumination with x-ray free electron lasers. These experiments allow us to access experimental systems having electronic temperatures of millions of Kelvin but ion cores that still rest on a periodic lattice. Such systems are a rich testing ground for theoretical treatments of partially ionized plasmas, such is important for several astrophysical problems and also the early stages of inertial confinement fusions.

Lab-based hard x-ray spectrometry

In the process of developing a test-bed for crystal monochromators, we realized modern spherically bent crystal analyzers provide the requisite efficiency and energy resolution to enable a laboratory-based hard x-ray absorption and emission spectrometer. In particular, using our nonresonant x-ray emission spectroscopy (XES) configuration provides count rates intermediate between a monochromatized bending magnet and monochromatized insertion device beamline at a 3rd generation synchrotron. The Seidler group has also published recent improvements that permit excellent scan-to-scan and sample-to-sample reproducibility. (see our publications). The instrument is continually being improved, and is in the process of conducting several studies, including those listed below. If you are interested in the possibility of measuring samples, please contact us.

• Examples of studies being done in hard x-ray spectrometer:
• In situ pouch-cell battery studies
• Transition-metal element studies in battery materials
• Chromium speciation in plastics/soils

Plasma Physics/Warm Dense Matter

Warm dense matter (WDM) is a transitional regime characterized by temperatures and densities intermediate between those of traditional condensed matter and plasma physics. WDM has attracted interest in recent years due to its importance to inertial confinement fusion and the modeling of physical systems found in planetary and stellar astrophysics. At the same time, modern laser plasma facilities and x-ray free electron lasers (XFELs) offer unprecedented experimental capability for producing WDM and probing its physical properties. The Seidler group’s work in this field includes both theoretical modeling of WDM, consisting of ab initio spectroscopy and finite-temperature DFT calculation, as well as experimental studies using X-ray pump-probe experiments carried out at the Linac Coherent Light Source (LCLS). We seek to develop modeling and experimental techniques that, in combination, enable better prediction and measurement of finite-temperature electronic structure and of the state variables of WDM.

CEI-Xanes

• CEI-XANES (Clean Energy Institute - X-ray Absorption Near Edge Spectrometer) is a user facility in the Molecular Analysis Facility (MAF) of UW, designed for rapid turnaround measurements of transition metals. The MAF employs a staff scientist, Liam Bradshaw, to lend expertise and assist in measurements. (link to CEI-XANES).
• CEI-XANES Site

Instrument Development

In support of the projects above, we are constantly developing and innovating on a variety of experimental techniques and apparatus.

• Several recent projects include:
• Lab-built hard x-ray spectrometer, XANES and XES
• Lab-built tender x-ray spectrometer, XES, 2-3keV
• CMOS-based, energy-resolving, small pixel x-ray camera and related software
• Development of crystal analyzers
• Low-absorption pouch cell for in situ battery studies