Interactive Tutorial about Diffraction Reciprocal space III: Rectangular lattice 

Reciprocal space
Interactive examples
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In this example an orthorhombic lattice is simulated. The vertical
unit cell length is half the horizontal unit cell length. Two by two
unit cells are simulated, each containing one atom at (0 0). This
miniature crystal is sufficient in size to illustrate the
geometrical relationships. By increasing the size, we will just
decrease the FWHM of the Bragg reflections. The units in the
pictures are given in unit cell units of the squared lattice in the
first example. The pictures below show the atoms and the
corresponding Fourier transform. Click on the pictures to get a
full screen version.
The reciprocal space geometry corresponds to that of the real space. The reciprocal base vectors are orthogonal to each other, but the vertical reciprocal base vector is twice as long as the horizontal. 
© Th. Proffen and R.B. Neder, 2003 