5. Diffraction Table of contents 5.1 Fundamentals 5.2 Characteristics of diffraction patterns 5.3 Structure factors 5.4 Structure solutions 5.1 Fundamentals Questions & answers π What is the relation between the Laue diffraction condition and the Braggβs equation? π Given a crystal with unit cell volume V and a wavelength Ξ» for the incident beam, how many different intensities can be collected in a diffraction experiment? π What is the Ewald sphere and how to use it? π In an X-ray diffraction experiment, is the wavelength of the incident and the diffracted beam the same? π How do I identify crystal patterns? π How is the Laue method used in studying crystals? π What difference would twinning make to powder diffraction pattern? π What are modern x-ray films made of (CR)? π How do you explain the differences of XRD peak intensities the same material? π What are k-alpha and k-beta peaks in the X-ray spectrum? Why do X-rays have a "continuous" spectrum? π What methodology and apparatus are used to analyze the crystal structure? π Is crystallography able to detect the presence of atoms other than carbon and hydrogen in a crystal? I mean atoms like fluorine, magnesium, etc. π How does powder crystallography work? How do we construct the crystal structure of the particles from the diffraction patterns observed? π What is the difference between X-ray crystallography and x-ray diffraction? π Is it okay to delete a substrate peak from an XRD pattern? If possible, which software can be used? π Why do crystals diffract X-rays? π In X-ray diffraction pattern, the position of peaks depend on what factor, the linear constant of the planes or the size and shape of crystal? 5.2 Characteristics of diffraction patterns Questions & answers π Why do we use (100) or other ways of showing for silicon crystals? Don't they all have the same spatial distribution? π What is an aperiodic crystal? 5.3 Structure factors Questions & answers π How can you calculate the structure factor for a 75% Ni 25% Fe DISORDERED system? π How many types of structure factors are there in crystallography? π What is the atomic structure factor in crystallography? 5.4 Structure solutions Questions & answers π The biggest problem in crystallography is solving the phases. Why is this not solved using principles that holography uses (the reference wave) for obtaining the phases? Are current x-ray sources not coherent enough, or is there another problem? π How can you obtain the crystal structure of a crystalline compound from the experimental diffraction data? π What is the charge flipping algorithm? π What is the name of the effect, which helps in determining the structure of ionic solid? π How can X-ray diffraction determine the crystalline structure of powders with randomly oriented crystals? π How do you calculate HKL values from XRD?
