- Ph.D., Nuclear Physics, Rutgers University, 1977
- B.S., Physics, Massachusetts Institute of Technology, 1971
Pink-beam focusing with a one-dimensional compound refractive lens
The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments.
Ultrafast x-ray-induced nuclear dynamics in diatomic molecules using femtosecond x-ray-pump–x-ray-probe spectroscopy
The capability of generating two intense, femtosecond x-ray pulses with a controlled time delay opens the possibility of performing time-resolved experiments for x-ray-induced phenomena. We have applied this capability to study the photoinduced dynamics in diatomic molecules.
Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics
New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena.
Resonance-mediated atomic ionization dynamics induced by ultraintense x-ray pulses
We describe the methodology of our recently developed Monte Carlo rate equation (MCRE) approach, which systematically incorporates bound-bound resonances to model multiphoton ionization dynamics induced by high-fluence, high-intensity x-ray free-electron laser (XFEL) pulses.
Dipole and nondipole photoionization of molecular hydrogen
We describe a theoretical approach to molecular photoionization that includes first-order corrections to the dipole approximation. The theoretical formalism is presented and applied to photoionization of H2 over the 20- to 180-eV photon energy range.
Feasibility of Valence-to-Core X-ray Emission Spectroscopy for Tracking Transient Species
X-ray spectroscopies, when combined in laser-pump, X-ray-probe measurement schemes, can be powerful tools for tracking the electronic and geometric structural changes that occur during the course of a photoinitiated chemical reaction.
Ultra-fast and ultra-intense x-ray sciences: First results from the Linac Coherent Light Source free-electron laser
X-ray free-electron lasers (FELs) produce femtosecond x-ray pulses with unprecedented intensities that are uniquely suited for studying many phenomena in atomic, molecular, and optical (AMO) physics.
Sequential multiple ionization and fragmentation of SF6 induced by an intense free electron laser pulse
We investigate the multiphoton ionization and the subsequent fragmentation of SF6 molecules with intense x-ray-free electron laser pulses at different photon energies. We observe highly charged molecular and atomic ions which were absent in previous experiments with conventional x-ray sources.
Spin-state studies with XES and RIXS: From static to ultrafast
We report on extending hard X-ray emission spectroscopy (XES) along with resonant inelastic X-ray scattering (RIXS) to study ultrafast phenomena in a pump-probe scheme at MHz repetition rates.
Multiphoton L-shell ionization of H2S using intense x-ray pulses from a free-electron laser
Sequential multiphoton L-shell ionization of hydrogen sulfide exposed to intense femtosecond pulses of 1.25-keV x rays has been observed via photoelectron, Auger electron, and ion time-of-flight spectroscopies.