Center for Functional Nanomaterials Seminar

Grazing-incidence x-ray scattering technique has greatly benefited from the high brilliance of the 3rd generation synchrotron radiation sources. With this technique, soft matter surfaces and thin films can be studied with much more elaborated spatial and temporal resolutions, giving rise to many new understandings of surface related phenomena. Several examples are given: 1) Grazing-incidence scattering combined with coherent x-rays allows one to follow surface dynamics at much smaller length scales than dynamic light scattering. Thermally excited surface capillary waves on films of entangled polymers were measured, and this revealed some new insights into the nature of glass transitions. 2) With many advantages, such as depth sensitivity, macroscopic length scale sampling, and flexible adaptability to various environments (e.g., vacuum and controlled gas ambient), grazing-incidence scattering in the small angle regime (GISAXS) has become one of the standard tools for structural characterizations of thin films with nanostructures. As an example, the kinetics of 2D Au nanocrystal superlattices self-assembled at the liquid/air interface were measured using in-situ time-resolved GISAXS, and the phase behaviors during the assembly were then determined. 3) In parallel, a multilayer GISAXS theory has been developed, and is ready for quantitative analysis of buried complex nanostructures in thin films.