Learning objectives
<p>to introduce the student to the theoretical and experimental knowledge of the main diffraction techniques and to their crystallographic applications to the determination (solution and refinement) of the crystal structure. </p>
<p> </p>
Prerequisites
basic knowledge of crystal symmetry
Course unit content
Introduction <br />
The Dirac delta function ; the lattice function; the Fourier transform and its application; the Fourier transform of a lattice function; convolutions; convolutions involving lattice functions; Fourier transform and convolutions <br />
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X-ray diffraction <br />
X-ray scattering; Thomson and Compton scattering ; interference of scattered waves; diffracton by a crystal; the atomic scattering factor; the temperature factor; the structure factor; symmetry in the reciprocal lattice; Friedel law; phase restrictions; systematic absences; diffraction intensities; the Lorentz-polarization factor; the transmission factor; dynamical aspectsi: primary and secondary extinctions, anomalous scattering and dispersion, Bijvoet pairs<br />
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Experimental aspects of X-ray diffraction <br />
X-ray generation; conventional sources; sinchrotron ligth; single crystal diffractometer; powder diffraction; powder diffractometer<br />
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Structure solution and refinement<br />
The Fourier synthesis and the phase problem in crystallography: sultution by trial and error; the Patterson function and its application in the structure solution; direct methods in crystallography; Wilson's stathistics and normalized structure factos; the Sayre equation, structure invariant and semi-invariants; probabilistic extimation of the invariant triplets; the tangent formula della tangente; phasing procedure; least squares refinement of the structureaffinamento strutturale con tecniche di minimi quadrati; Rietveld refinement of powder data.<br />
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Neutron diffraction<br />
The neutron-matter interaction; elastic and inelastic scattering ; the neutron scattering factor; magnetic scattering ; neutron sources; neutron vs. X-ray diffraction. <br />
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Electron diffraction<br />
Kinematic theory of electron diffraction; the electron scattering factor; dynamical diffraction; the transmission electron microscope; HREM; electron crystallography. <br />
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Practice: instrumentation, data collaction, structure solution and refinement<br />
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Full programme
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Bibliography
<p>Fundamentals of crystallography, C. Giacovazzo, H.L. Monaco, D. Viterbo, F. Scordari, G. Gilli, G. Zanotti, M. Catti, Eited by C. Giacovazzo, International Union of Cristallography, Oxford Science Publication <br />
ISBN 0 19 855578 4 <br />
</p>
<p>lesson notes</p>
Teaching methods
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Assessment methods and criteria
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Other information
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