Interactive Tutorial about Diffraction Interactive example: Phase angles III 

Phase problem
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In this interactive example you should investigate the effect of
the atom position on the amplitude and phase angle of a single
Bragg reflection.
The controls on the simulation window allow you to create a single
electron a single Si or a single Pb atom located within a unit cell.
The unit cell represents a cubic crystal of 10 Angstroem lattice
constants. The position of the atom/electron is given in fractional
coordinates. You can also select whether to calculate Xray or neutron
intensities.
Four diagrams will be plotted. The first displays the position of the
atom, the second (the lower left diagram) displays the position of
the Bragg reflection in reciprocal space. The third diagram (upper right)
shows the real and imaginary part of the Bragg reflection in the
complex plane. The xaxis
reflects the real part, the yaxis the imaginary part of the
structure factor. The angle between the positive xaxis and the
structure factor represents the phase angle. The final diagram displays
the corresponding numerical values. Start exploring and try to answer the questions below:

© Th. Proffen and R.B. Neder, 2003 