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Stephen H. Southworth

Senior Physicist


Stephen Southworth is a Senior Physicist in the Atomic, Molecular and Optical Physics group.  His research interests are in x-ray and inner-shell physics of atoms and small molecules.  He conducts experiments using synchrotron x-rays and x-ray free-electron lasers and collaborates with theorists to characterize and understand basic physics.  In addition to experiments on gas-phase atoms and molecules, his recent research includes high-resolution x-ray spectroscopies of actinide compounds and of laser-excited molecules in liquid solutions.


  • Ph.D, Chemistry, University of California, Berkeley, 1982
  • B.A. (Honors College), Chemistry, University of Oregon, 1977


Recent Publications

Observation of the fastest chemical processes in the radiolysis of water, Z.-H. Loh et al., Science 367, 179 (2020).

Observing pre-edge K-shell resonances in Kr, Xe, and XeF2, S.H. Southworth et al., Phys. Rev. A 100, 022507 (2019).

Micro-focused MHz pink beam for time-resolved x-ray emission spectroscopy, M.-F. Tu et al., J. Synchrotron Rad. 26, 1956 (2019).

Three-dimensional optical trapping and orientation of microparticles for coherent x-ray diffraction imaging, Y. Gao et al., Proc. Natl. Acad. Sci. 116, 4018 (2019).

Relativistic and resonant effects in the ionization of heavy atoms by ultra-intense hard x-rays, B. Rudek et al., Nat. Commun. 9, 4200 (2018).