Research Interest

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Research Interest

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The XD Programming Package

UBDB-Buffalo Aspherical Atom Databank

Dr. Coppens' Group  

Crystallographic Links

Relativistic Scattering Factors

Relativistic Scattering Factors for Ions

Analytical Fit to Relativistic Scattering Factors

Analytical Fit to Relativistic Scattering Factors for Ions

Analytical Wave Functions for Relativistic Atoms

  • Studies of Laser-Generated Excited States by X-ray Diffraction. 
  • Use of Synchrotron Radiation in Crystallography. 
  • Experimental Mapping of the Electron Density. 
  • Organic Conductors and Metal-Insulator Transitions. 
  • Development of Methods for Accurate Integration of Area Detector Images. 

 Our work includes the development of new experimental and theoretical methods for the study of solids by X-ray diffraction, including the use of very high intensity sources and liquid-helium temperature diffraction equipment. When necessary, experiments are performed at the SUNY X3 beamline at the National Synchrotron Light Source at Brookhaven National Laboratory. Two of the diffractometers in Buffalo are equipped with the same software, electronics and computer hardware as our single-crystal synchrotron instruments at NSLS. In this way students and others can be trained, and perform preliminary experiments before going to NSLS.

 We use light excitation of diffractometer-mounted crystals, kept at low temperatures, to study the nature of short-lived species. With the rotating anode source and a mechanical light chopper, we can study the geometry of millisecond lifetime excited species. We will use the time structure of the Advanced Photon Source to extend the studies to transient species with shorter lifetimes.

 The use of X-ray diffraction in the mapping of electron densities sheds new light on the chemical bonding in molecules and the properties of crystalline materials. The electron density directly gives information on the nature of chemical bonding, which is important for the understanding of properties of materials. Recently, we have focused our attention on the derivation of electrostatic properties, such as dipole and quadrupole moments and the electrostatic potential, directly from the X-ray data. In the future work we intend to combine time-resolved studies of transient species, with the analysis of electron density changes upon molecular excitation.