My research interests are focused on using synchrotron radiation for element specific characterization (spatial, electronic, quantitative) of novel materials including optical coating-substrate systems, functionalized nanoparticles, and hydrogen fuel-cell cathode/anode materials using a hard x-ray techniques including extended x-ray absorption fine structure (EXAFS), x-ray absorption near-edge spectroscopy (XANES), x-ray diffraction, and x-ray fluorescence. In addition to experimentation, there is also molecular modeling and multiple-scattering calculations of x-ray absorption spectra and electronic structure. FEFF, an ab initio multiple scattering code that utilizes Green’s function to simulate the absorption coefficient of model atomic systems is one of the tools used to simulate novel chemical systems. In these calculations we utilize the code to generate XANES spectra and to calculate the local density of states about the absorbing atom. For ordered systems, we use standard crystallographic data to generate coordinates of a central absorbing atom and its neighbors. The area of interest is the spectral region near the absorption threshold of a core electron of a central atom. The simulated XANES spectra represent the excitation a core electron, its promotion to quasi-bound states and its eventual ejection into the continuum. These data lend insight into the local chemical environment of the system of interest. One of the systems of interest is titania (TiO2)-doped tantala (Ta2O5) multilayers fabricated via ion beam sputtering on SiO2 substrates. Additionally, metal oxide nanoparticles are of interest for a host of reasons, including applications involving catalysis, and their useful electronic and optical properties. To this end we are employing synchrotron-based X-ray absorption Spectroscopy (XAS) techniques including Extended X-ray Absorption Fine Structure (EXAFS), X-ray Absorption Near Edge Structure (XANES) and X-ray Fluorescence (XRF) to examine our samples.
