Diffuse scattering
Thermal I
Thermal II
Occupational I
Occupational II
Longitudinal waves
Transversal waves
Short range order
Stacking faults
Interactive examples
Displacement waves
Short range order
Stacking faults
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Contents

 Example 1: The propagation
direction determines the directions in which the satellites are
observed, the wavelength determines the distance from the Bragg
reflections. The oscillation direction on the other hand determines
the direction of the intensity modulation of the Bragg and satellite
peaks. The phase has no influence on the observed intensities.
Be careful when changing the wavelength. If
it gets too short with respect to the lattice parameter (5A), the
wave has no sinusoidal character any more and one can e.g. observe
different satellite intensities at +k around the Bragg peak !
 Example 2: The patterns can be generated
using the correlations (i) all 0.0, (ii) a100 positive, rest 0 for chains
of a200 negative for pairs, (iii) a100,a010 negative and a110,a110 positive
and (iv) all positive.
A positive correlation a100 for example creates diffuse streaks through
the Bragg peaks parallel to k and a negative a100 will give the same streak
between Bragg peaks. One can think of this as a local doubling of the unit
cell creating 'new' Bragg peaks at half positions. For more details review
the analytical expression given in the SRO
section of the tutorial. It should also be noted that the scattering
intensity is symmetric around the Bragg positions. Finally the extend
of the short range order and the width of the diffuse features are
reciprocal to each other, sharp features in reciprocal space
correspond to 'longer range' disorder and vice versa.
