UC San Diego

There is the diverse range of disciplines studying various topics using x-ray techniques. Now, with the development of third-generation synchrotron sources, we can conduct experiments which require special properties of x-ray beam, such as coherence and polarization for studying materials characterization, structural changes, molecular or spin dynamics and so on. In this thesis, we would present the results of structural and dynamic studies by synchrotron-produced x-ray sources. First, the lipid phase-separated bilayers are studied by resonant soft x-ray scattering. In the novel finding, we find the domains of the so-called liquid ordered phase in the phase-separated mixed lipid-cholesterol multilayers constitute sub-domains which are three-dimensionally ordered. This is one of the few examples of ordered liquid phase within another liquid phase. This offers the possibility for the development of novel materials. We also discuss the utilization of coherent x-ray beams to study the dynamics of nanoparticles in polymer melts and magnetic spins in spin glass systems. The nanoparticles show different diffusive and often novel behaviors depending on the entanglement and the heat treatment. Studying the spin structures of spin glass is always interesting and challenging. Up to now, the detailed observation of spin glass phase transition associated critical behaviors have elucidated experimental studies, such as neutron scattering. Using coherent x-rays, we have been able to couple directly to the critical fluctuations of the so-called Edwards-Anderson (EA) order parameter and have observed the dynamical critical behaviors for the first time.