Ultrafast X-ray Studies of Condensed Matter Systems in and out of Equilibrium
Over the last century or so, the diffraction of X-rays from periodic structures such as crys- tal lattices has yielded a vast number of breakthroughs in our understanding of condensed matter systems and how they are ordered. Over the course of this history, technical advances in the way X-rays are produced and measured have allowed for the structural characteriza-
tion of solids to occur more and more rapidly. While clearly yielding an improvement in efficiency, the true scientific value of these advances is to allow determination of structural changes at shorter and shorter intervals. The capabilities of modern X-ray sources are now becoming so advanced that it is possible to measure dynamics on the order of picoseconds, al- lowing scientists to measure “fundamental” phenomena not possible before, such as fast phase transformations and shockwaves. Dynamical studies of solids are naturally grouped into two categories: equilibrium, and non-equilibrium. This thesis is divided along the same lines. In the first part, a proposal is presented describing a new statistical method for studying equi- librium dynamics that could be implemented in the near future. In the second, experimental results showing the ultrafast propagation of an induced acoustic shockwave in a Chromium thin film are presented. This experiment was performed at the cutting-edge Linac Coherent Light Source (LCLS) at Stanford.