2019 Physics/Theoretical Colloquium

 

Thursday, March 7th , 2019

3:45 – 4:45 p.m.

Rosen Auditorium (TA-53, Bldg. 1)

Refreshments at 3:15pm

 

Speaker:  Dr. Stefan Hau-Riege

 

Lawrence Livermore National Laboratory, Livermore, CA 94550

 

“Interaction of high-intensity x-ray pulses with matter "

 

 

 

Abstract: 

In this presentation, we will review our recent work on the interaction of high-intensity x-ray pulses, as produced by x-ray free-electron lasers (XFELs), with matter. Various XFEL facility have come online worldwide over the last few years. They deliver x-ray pulses that are multiple orders of magnitude brighter than synchrotron radiation and have durations of tens of femtoseconds or less. Several different ultrafast physical processes occur when this kind of radiation interacts with materials. Of particular importance are electron heating by the x-rays, atomic relaxation, electron-ion equilibration, as well as energy transfer and atomic/ionic motion. We have studied these processes using computational methods as well as experiments at soft and hard XFEL facilities.  The applications we focus on in this presentation include (i) the development of damage-resistant optical materials for the x-ray regime, including crystals, multilayer mirrors, and solids, (ii) damage processes in biological materials relevant to protein structure determination, and (iii) fundamental condensed matter physics. In particular, our review will include recent results on x-ray-induced non-thermal melting. To study this, we built and fielded a sub-picosecond x-ray delay line called MEL-X at the Linac Coherent Light Source (LCLS) last Fall.

 

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.