Ultrafast Special Interest Group

The Ultrafast Special Interest Group is organized around ultrafast and time-resolved science at Argonne, including experimental techniques that use the pulsed structure of the APS and related ultrafast laser-based methods to study phenomena from femtoseconds to microseconds. Seminars are hybrid and announced via the APS Beamline Personnel, APS Resident Users, and Seminars mailing lists.
Chairs
•    Tyler Haddock ([email protected])
•    Cunming Liu ([email protected])
 
Upcoming Seminars

Monday, October 5, 2026 — 12:00 PM CDT

Speaker: Dr. Gilles Doumy (Argonne National Laboratory, CSE)
Host: Tyler Haddock
Location: Building 436, Room C010, and Microsoft Teams
Title: Exploration of non-linear resonant x-ray excitation mechanisms 
Abstract:
The resonant interaction of x-rays with matter is central for exploiting site selectivity in molecular systems. However, this interaction remains largely unexplored when subjected to intense x-ray pulses, which can trigger subsequent processes such as stimulated emission, stimulated x-ray Raman scattering, induced resonances, and multiple resonant excitations. We demonstrated experimentally, in the gas phase, that fully resonant sequential multi-core excitations to exotic neutral multi-core excited states are feasible. Using intense short x-ray pulses from XFELs in one- and two-pulse schemes, we generated these doubly excited states and characterized their unique electronic decay signatures. This work furthers the development and extension of common state- and site-selective x-ray techniques into nonlinear spectroscopies. 

Thursday, October 29, 2026 — 2:00 PM CDT

Speaker: Professor Dugan Hayes (University of Rhode Island)
Host: Tyler Haddock
Location: Building 432, Room C010
Title: TBD 
Abstract:
TBD