Facility Description: Scientific Discovery Opportunities
The underlying theme of the grand challenges now being posed for physics, chemistry, and materials science is to understand, predict, and ultimately control the properties of matter. The “emergent” properties of complex systems are of particular interest. Here, correlated interactions among charge carriers, and between charge carriers and constituent atoms, give rise to new properties and functionality with tremendous potential for practical applications. These same correlated interactions also challenge our understanding of complex systems in that they defy conventional paradigms based on the Born-Oppenheimer approximation, single-electron band structure models, Fermi liquid theory, etc. These problems cry out for tools that are sharper than those currently available.
To meet these challenges we must answer fundamental questions about the coupling between the correlated motion of electrons and the motion of atoms. The intrinsic time scales of those motions, differing as they do by three orders of magnitude, require both femtosecond and attosecond time resolutions. The need to directly probe electronic structure and dynamics demand a focus on the VUV and soft x-ray regions, and the creation of experimental facilities that complement those being constructed with hard x-ray capabilities.
It is clear that in the future, direct quantitative measurements of the electronic and atomic structural dynamics on the ultrafast time scale of the underlying correlations will be indispensable for achieving new insight into the physics of complex systems and novel properties emerging from correlated phenomena in atoms, molecules, and complex solids. Thus, there is a strong scientific need to be able to probe matter with atomic spatial resolution, elemental specificity, meV energy resolution, momentum resolution, and ultrafast time resolution, in order to separate correlated phenomena in the time domain. Time resolution, high average flux, high repetition rate, high resolving power, and soft x-ray tunability emerge as critical needs. These needs are not fully met by existing or planned research facilities within the United States, and sources complementary to the third generation light sources and the LCLS are required.
