Events

The Cole-Cole model is known to accurately describe the dielectric response of a dispersive material over a wide range of frequencies. The model, however, does not lend itself easily to time domain simulation methods such as the Finite Difference Time Domain (FDTD) method, as it involves the approximation of fractional-order derivatives. Researchers have instead often used the Debye model, which is characterized by the same dielectric parameters as the Cole-Cole model, but has less accuracy in describing the dielectric response.

The arrow of time manifests itself in a broad range of phenomena. It may be an essential ingredient that provides the underlying structure to space-time, directs a sugar cube to dissolve in a cup of coffee, and allows us to remember the past but not the future. While the microscopic processes involved are reversible, what we experience in the macroscopic world is not: a sugar cube is never observed to spontaneously emerge from a hot beverage.

Proteins are complex polymers consisting of thousands of atoms. Out of the many possible conformations of such a molecule, usually only a few or perhaps just one (the "native" conformation) is significantly populated. Proteins interact extensively to form complexes, but in precisely defined ways. Both proper folding and proper specificity of interaction are essential for biological function. Nuclear Magnetic Resonance (NMR) is a powerful tool for the study of protein conformations and interactions.

Simple -- and often used -- electrostatic arguments suggest that polar surfaces of insulators are unstable. Experimental studies, however, have demonstrated that polar surfaces of oxides such as MgO do exist. Moreover, the structure and growth of thin films on these polar oxide surfaces can be quite different than on the non-polar surfaces.

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Metamaterials � nanostructured composites with engineered electromagnetic response promise to provide solutions to several fundamental problems of light-matter interaction, enabling such exotic applications as planar lenses, superlenses, and optical cloaks. This talk will be focused on the physics and applications of a subclass of metamaterials, anisotropic composites. Several designs of anisotropic structures will be presented and their unique optical properties will be discussed.

My talk will begin with a "Why neutrons?" overview of basic neutron scattering physics facts, and of neutron scattering techniques used for investigating condensed matter systems. Next, I tell about spintronics -- its advent, its current status, and about successes and challenges on the road to developing semiconductor spintronics. In this context I will then present research on magnetic semiconductors that our OSU neutron scattering team conducts.

Organic semiconductor materials have attracted significant attention in recently as they offer significant advantages over traditional silicon technology including their low cost fabrication and tunability through functionalization of the molecules. Envisioned applications range from inexpensive solution processable solar cells to rewritable holographic displays. However, despite this interest in application, the nature of charge carrier photogeneration and transport in organic semiconductors is not completely understood and remains controversial.