The extreme peak power of the LCLS beam creates utterly new challenges and research opportunities in atomic physics. The first LCLS experiments will produce and study atoms in excited states never before accessible in the lab. For example, it will be possible for the first time to observe the behavior of atoms that have absorbed many x-rays in rapid succession or atoms that have been struck simultaneously by two x-rays. The LCLS will have sufficient intensity to eject ALL the inner-shell electrons from an atom, producing "hollow" atoms.

The unique features of LCLS will make it possible to produce energetic clusters of atoms with high charge states that will undergo giant coulomb explosion. This experiment is of key importance in understanding energy transfer and radiation damage of the LCLS beam in clusters, molecules and particles. Advanced research topics include studies of radiation and possibly lasing from XFEL-excited matter and the formation of highly excited laser plasmas.

The LCLS gives us information about molecules and plasmas as a result of the interaction of its x-ray beam with atoms – more specifically with the inner shell electrons of the atoms in the sample. In this sense, atomic physics is at the heart of all LCLS science; atomic physics experiments are needed to lay the foundation for any materials science experiments with the LCLS. Indeed, the LCLS is so intense that scientific research with this new tool will begin with study of the performance of the mirrors, lenses, filters and masks necessary to transport and condition the beam.

Concepts for producing even shorter x-ray pulses with the LCLS are currently under development. With pulses in the range of 1 femtosecond, it will be possible to catch a glimpse of how electrons move within an atom as it transits from one state to another.