The objective of our research program is to advance fundamental understanding of the interaction of atoms, molecules, negative ions and clusters with vuv/soft x-ray photons. The goal of the program is to investigate, at the atomic and molecular level, processes important to the understanding of the properties of complex systems including materials, with unprecedented level of detail. To carry out our research, we take advantage of the new frontiers opened for research in science. One of these frontiers is third generation light sources that permit the development of new spectroscopic tools and new methods for the quantum control of atomic, molecular and small clusters processes. In our research program, we use the brightness, spectral resolution, tunability and polarization of the Advanced Light Source (ALS) synchrotron radiation facility, at the Lawrence Berkeley National Laboratory, to study with unprecedented level of detail, multi-electron excitation via inner-shell photoionization. We combine this state of the art source with high-resolution differential detection techniques, including imaging methods, for the characterization and visualization of structures and properties, to probe the many-body problem from the atomic to the nanoscale system.

These past 2 years, we have included in our research program plans to study ultrafast phenomena using femtosecond free electron lasers (FEL). In particular, our research interests, in fundamental light-matter interactions, include now the control of quantum systems using ultrafast light sources. This future research will allow ultrafast studies, strong field as well as pump-probe experiments in an energy regime never attained before and should generate new physics. The experiments will focus on inner-valence, K-shell and inner-shell excitation and ionization of atoms, molecules and clusters and their ions using vuv (presently at FLASH in Germany) and XFELs at SLAC, Stanford, CA.

We have 7 experimental apparatus which we use at the ALS:

• 2 long (647mm) TOF analyzers positioned 125.3^o apart, in a rotatable chamber, allowing simultaneous measurements to be made at, for eg., 54.7^o (magic angle) and 0^o with respect to the polarization vector of the incident radiation.
  
• 4 short TOF analyzers positioned at a variety of angles to allow coincidence measurements to be made between electrons ejected at various mutual angles.
  
• Mott TOF analyzers to measure electron spin polarization of selected photolines and Auger transitions.
  
• A rotatable Scienta (SES-200) hemispherical analyzer capable of colleting very high resolution photoelectron spectra (PES) at selected photon energies over a wide range of electron kinetic energies.
  
• A rotatable home built hemispherical analyzer based system, fitted with an Integrated Sensors Limited position sensitive detector, is used to collect electrons of low kinetic energy (0 - few eV) and employs a two dimensional scanning technique during data acquisition.
  
• An ion-photon beamline, a shared facility between WMU and UNR (built by the Phaneuf group, UNR), to which we have added negative ion sources to study inner-shell photodetachment.
  
• Imaging techniques and e-ions as well as ion-ion coincidence techniques.