We consider scattering by short range perturbations of the semi-classical Laplacian. We prove that when a polynomial bound on the resolvent holds the scattering amplitude is a semi-classical Fourier integral operator associated to the scattering relation near a non-trapped ray. Compared to previous work, we allow the scattering relation to have more general structure.

Motivated by surface x-ray scattering experiments on homoepitaxially grown Ag(001), scattering models for surfaces having submonolayer coverages are discussed in the context of small angle scattering. It is shown that the surface diffuse line shapes can be interpreted in terms of intraisland and inter-island scattering. The connection between these models and other surface experiments is also d...

The afterglows of gamma-ray bursts (GRBs) have been commonly assumed to be due to shocks sweeping up circum-stellar medium. However, most of them have been found to be hosting in dense star-forming regions where a significant fraction of the prompt X-ray emission can be scattered by dust grains. Here we revisit the behaviors of X-ray dust-scattering in GRBs. We find that the features of some X-...

The increased coherence of third generation synchrotron sources allows us to port laser techniques such as holography and dynamical light scattering from the visible to the x-ray spectral range. In addition to the obvious improvement in resolution, the x-ray range may allow for new variants that are not possible in the visible, as exemplified by techniques that use the strong magnetic contrast ...

We have studied the X-ray dust scattering halos around 17 bright X-ray point sources using Chandra data. All sources were observed with the Advanced CCD Imaging Spectrometer and High-Energy Transmission Grating in Continuous Clocking Mode (CC-mode) or Timed Exposure Mode (TE-mode). We use an iterative method to resolve the halos at small scattering angles from the zeroth order data in CC-mode o...

In this research program, modern x-ray scattering techniques are used to study the structures and phase transitions in novel states of condensed matter. We have two principal experimental facilities. At M.I.T. we have two high-resolution computer controlled x-ray spectrometers using a high intensity rotating anode x-ray generator. Two more spectrometers are currently under development. The angu...

A model for a three-component plasma consisting of two distinct ionic species and electrons is developed and applied to study x-ray Thomson scattering. Ions of a specific type are assumed to be identical and are treated in the average-atom approximation. Given the plasma temperature and density, the model predicts mass densities, effective ionic charges, and cell volumes for each ionic type, to...

Green nano pigments of Cr2O3 and CoCr2O4 were successfully prepared by polyol method followed by calcination at 770°C. The Cr2O3 and CoCr2O4 samples were characterized by X-ray diffraction XRD, scanning electron microscopy SEM, diffuse reflectance spectroscopy DRS, dynamic light scattering DLS, UV–Vis spectroscopy and CIE-Lab colorimetry methods. Dynamic light scattering analysis confirmed the f...

A new fundamental parameter method which employs measured Comptonand Thomson scattered characteristic tube line intensities for the estimation of non-measuring matrix elements has been developed. The concept of substituting a compound matrix by a single element of average atomic number has been efficiently applied to the analysis of biological samples, polymers, liquids, and powders where the n...