in Engineering and Applied Science at Caltech. in Materials Science and Engineering at Stanford University, and B.S. in Physics from University of Houston, M.S. So, the total coherent intensity Icoh for the non-interacting electrons is given by. She started her scientific career at IBM Research Laboratory in New York, moving from there to Polytechnic University in Brooklyn and subsequently to NIU. similar to the form factor f1 (4.13) obtained for oneelectron atom. Department of Energy, Office of Science, Basic Energy Sciences, Division of Materials Sciences and Engineering.Ĭarol Thompson, Professor of Physics at Northern Illinois University, is an experimental materials physicist. In this talk I describe these new developments in x-ray studies, and present our simulations and initial measurements of x-ray coherent scattering from dynamic crystal surfaces under in-situ conditions within a metal-organic chemical vapor deposition chamber. With this goal, an Argonne-NIU collaboration has begun exploring how coherent x-ray studies can be applied to studies of crystal growth. ![]() The expected increase in coherent flux at high x-ray energy delivered by facilities such as the Advanced Photon Source at Argonne National Laboratory opens up the possibility that these novel techniques can be applied to in-situ studies of dynamic surfaces in complex process environments. For non-equilibrium surfaces as during crystal growth, the two-time and other higher-order correlation functions extracted from x-ray photon correlation spectroscopy may elucidate aspects of island nucleation, step-edge barriers, and transport mechanisms. For equilibrium crystal surfaces at high temperature, x-ray ‘speckle’ correlations should reveal the dynamics of defects such as steps and adatoms. These coherent x-ray techniques probe dynamics. A new development in x-ray science is the use of coherent x-ray beams for techniques such as x-ray photon correlation spectroscopy and coherent diffraction imaging. The penetrating nature of high-energy x-rays allows investigations using realistic process environments and conditions, and their short wavelength provides sensitivity to atomic-scale structures and correlations. X-rays provide powerful tools for in-situ time-resolved studies of interface and surface evolution during materials processing. Carol Thompson, Professor in the Department of Physics at Northern Illinois University. Coherent scattering is not a major interaction process encountered in radiography at the energies normally used.Ĭoherent scattering varies with the atomic number of the absorber (Z) and incident photon energy (E) by Z/E.ND Energy invites all Notre Dame researchers to the following discussion by Dr. ![]() The only change is a change of direction (scatter) of the photon, hence 'unmodified' scatter. There is no energy deposition and thus no dose resulting from coherent scattering. X-ray Resonant (Coherent) Scattering is the technique of choice to probe such phenomena thanks to its element-selectivity and spatial sensitivity. the photon energy is well below the binding energy of the electron) so no energy transfer occurs. Upon interacting with the attenuating medium, the photon does not have enough energy to liberate the electron from its bound state (i.e. Coherent scattering (also known as unmodified, classical or elastic scattering) is one of three forms of photon interaction which occurs when the energy of the x-ray or gamma photon is small in relation to the ionization energy of the atom. It, therefore, occurs with low energy radiation.
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