Experimental Investigation of Ultrafast Hydration Structure and Dynamics at Sub-Angstrom Lengthscales

This thesis outlines how meV-resolution inelastic x-ray scattering and causality-enforcing mathematics can be used to measure the dynamical density-density linear response function for liquid water with Angstrom spatial resolution and 50fs temporal resolution. The results are compared to high-resolution spectroscopic and scattering experiments and simulations on liquid water to relate observed density fluctuations to the underlying molecular motions. The response function is used to image the dynamical hydration structure around dynamical point charge distributions. It is shown that the direct application of linear response theory to extended sources is unable to reconstruct known hydration structures due to the lack of a description of excluded volume. Finally, a simple implementation for excluded volume is proposed that treats excluded volume as an epsilon = 1 cavity. The complete linear response and excluded volume (designated Green's Function Imaging of Dynamics, or GFID for short) approach is applied to simple static and dynamical cases like the hydrated electron and ions. Relevant reviews of water and inelastic x-ray scattering are also included. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]