In the last few years our primary interests have been in understanding surface and thin film growth and patterning processes using synchrotron-based x-ray scattering. In collaboration with Randall Headrick (University of Vermont) and Matthew Dawber (Stony Brook University), we are Partner Users on the ISR beamline 4-ID at the National Synchrotron Light Source-II (NSLS-II – Brookhaven National Laboratory). There we are using a custom surface diffractometer on which we have been performing real-time “non-coherent” x-ray studies of ion beam nanopatterning, in collaboration with the group of Stefan Facsko at the Helmholtz-Zentrum Dresden-Rossendorf, and epitaxial III-nitride growth by plasma-assisted atomic layer deposition, in collaboration with the group of Charles Eddy at the Naval Research Laboratory.
Most recently, we have been collaborating with the Headrick group to develop the application of the coherent x-ray scattering technique of X-ray Photon Correlation Spectroscopy (XPCS) to better understand surface growth processes, utilizing the 8-ID beamline at the Advanced Photon Source (APS – Argonne National Laboratory) and the CHX beamline 11-ID at the NSLS-II. Traditional “non-coherent” x-ray scattering yields information about the average structure of a sample; therefore real-time scattering can show the “kinetics” — the change in average structure. In contrast, coherent scattering is sensitive to the exact structure and can thus yield information about fluctuations around the average, i.e. the underlying dynamics.