In Simple Terms

The X-ray Sciences and Techniques group of SIMES is devoted to both experimental and theoretical advancements of X-ray spectroscopy, scattering, and imaging techniques. These techniques offer unprecedented insights into charge dynamics in materials, and span areas from fundamental science to applied materials and devices. We take advantage of two important Department of Energy (DOE) photon science user facilities at SLAC (SSRL and LCLS), as well as other cutting edge theoretical capabilities. We also leverage efforts with other DOE user facilities, such as the Advanced Light Source at Berkeley. The advanced X-ray capability is essential to address all 5 grand challenge problems because of its ability to reveal atomic and electronic structures on ultrasmall and ultrafast length and time scales.

Scope of Research

The overall scope of this subgroup's investigations involve the development and use of X-ray probes to explore and understand the nature of electronic structure and dynamics of novel materials of relevance to the energy science mission of the Department of Energy. A detailed study of electronic, geometric, and excitation properties of crystals, films, surfaces, interfaces, and complex nano-assemblies of atoms has been enabled by advances made in a panopoly of X-ray experimental and theoretical techniques. These techniques have offered unprecedented insight into the nature of how quantum control over electrons and atoms can be achieved as external parameters, relating to materials growth, temperature, magnetic fields, pressure, and photon-pulses, are varied. For example this includes time-resolved pump-probe angle-resolved photoemission, X-ray absorption studies of matter under high pressure, and nanoscale X-ray imaging of magnetic structures in buried interfaces. Supported by numerical simulations, these novel applications of photoemission and X-ray microscopy on the nanoscale provides for detailed inspection of how local variations of environment influence control over local electronic bandstructure, excitation dynamics, and materials properties.

Research Areas

The program consists of six core research areas, interwoven to provide complementary studies reflecting our strengths in computational simulations, high resolution photoemission, X-ray spectroscopy, and coherent X-ray imaging.

• Computational simulations and development of theories for X-ray based scattering and spectroscopies
• Ultra-high resolution momentum, energy, spin and time-resolved photoemission spectroscopy
• X-ray spectroscopy of novel materials under extreme pressure
• Coherent X-ray imaging of magnetism and magnetic materials
• Inelastic X-ray scattering
• In-situ X-ray spectroscopy and scattering measurements

These studies are inherently multidisciplinary in the fields of materials, earth and energy science, physics and chemistry. Opportune collaborations among researchers spring naturally from the commonality of techniques used by the group. The fruit borne from the efforts of our group provide comprehensive studies of a variety of materials viewed from diverse and complementary vantages offered by interrelated X-ray techniques. The group synergy helps to chart new directions of experimental and theoretical techniques to expand the scope of investigations and the insights obtainable from novel uses of X-rays from synchrotron light sources to push the forefront of energy science. In the near future, we plan to expand our activities to include soft X-ray scattering using the LCLS.