Sai Nandyala

 Determination of crystal structure internally  Every lattice plane behaves like a diffraction grating when X-rayed  Position of spectral likes depend on distance between lines and so the nature of X-ray depends on the spacing between planes

 (pic 5.1)  Monochromatic xrays  FCD, FC’D, FC’’D are path lengths  FC’D is larger than FCD by AC’B  AC’B = 2AC = 2dsin#  N(lamda) = 2dsin#  Bragg’s Equation  N-integral number lamda – wavelength  (Eq of f)  F = sf = mean amp. Of waves scattered  W(r) = prob. Of finding e- bw two shells

 Laue Photographic Method  Rotating Crystal Method  Oscillating Crystal Method  Powder Method

 Tiny crystal on narrow incident beam from filament to diff beam on p plate  Laue pattern appears  #, d(spacing), is found  (pic)

 Beam penetrates at 90” where crystal rotates on axis // to axes  During rotation, diff positions show diff spots on p plate  (pic)  Terms of layer lines

 Crystal at 10” to 20”  Reflecting positions exposed and is lim.  Cylindrical p plate

 Powdered samples  Beam to powder to diff ray to strip to diff rings  Simplest to work  Work when crystals uneasy to get  (pic)

 Identify crystaline phases and orientations  Determine atomic arrangement  Measure thickness of films  Determine structural properties