Time-Resolved Opportunities at the APS and Beyond: Upgraded Capabilities and Compact X-ray FEL Visions (WK#3 | 2026 APS/CNM user meeting)

Generating the Fastest X-ray Pulses—Advances in Attosecond Inner-Shell X-ray Laser Science

May 6, 2026, 2:15 PM

25m

Building 402 Lecture Hall

Speaker

Uwe Bergmann (University of Wisconsin, Madison)

Description

We present our progress in exploring the phenomenon of stimulated x-ray emission spectroscopy (S-XES)
based on inner-shell lasing at 6 – 8 keV as a new spectroscopy tool, and as a new source of ultrafast hard x-ray
pulses. We first discuss the principle of S-XES, and the experimental methods required for generating and
measuring it. We then discuss recent results for spectroscopy applications of S-XES and its potential and
challenges of providing enhanced electronic structure sensitivity. We then discuss applications of S-XES as a
powerful new x-ray source for probing attosecond dynamics. Here we present the observation of strong lasing
effects and a new technique, x-ray coherent attosecond pulse pair spectroscopy (X-CAPPS) enabling
interferometry for probing phenomena in the 500 attosecond to 5 femtosecond time window. Finally, we
describe the XFEL parameters that would be ideal for advancing the described research.