© Steffen Weber, July 1997, (update 10/24/01)
I am in the process of updating this applet ..., so this is a beta version
This applet simulates X-ray Diffraction patterns for
the Laue method (transmission/backreflection mode). NOTE
on the quasicrystal systems:
-you may select among the octagonal (8fold), decagonal (10fold),
dodecagonal (12fold) and icosahedral systems
-the capital letters 'S:' and 'Y:' indicate the usage of
STEURER's or YAMAMOTO's lattice matrices
Film size and Film distance
The Film size is set as 120 x 120 mm. The film-sample-distance (FSD) is
set as 50 mm. Therefore in transmission mode reflections with theta<=25 deg
and in backreflection mode reflections with theta>=65 deg are plotted.
NOTE on STEURER and YAMAMOTO matrices:
- the two leading authorities on numerical structure analysis of quasicrystals
are Dr.Akiji Yamamoto and Prof.Walter Steurer
- they use different lattice matrices
- their lattice constants 'a' are not the same
NOTE on the OCTAGONAL, DECAGONAL, DODECAGONAL system:
- do use 5 integers for the orientation vector (separate
components by SPACE)
- give 'a' & 'c' as lattice constant
NOTE on the ICOSAHEDRAL system:
- do use 6 integers for the orientation vector (separate
components by SPACE)
- give 'a' as lattice constant
NOTE on the maximum order:
-due to the loop over 5 or 6 integer indices the number of
generated poles might be high. I reseved arrays for upto 10.000
poles. The calculation might be very time consuming though.
Therefore I recommend not to exceed max.oder=1 (icosahedral
system) or max.order=2 (for the other systems).
NOTE on the indices:
- just click the poles to get their indices.
NOTE on max. qi:
You may limit the number of generated reflections by setting
smaller values for the internal space component of the
diffraction vector q. This is reasonable since reflections
with large internal space components are weak and often not
observable. NOTE on spot radii:
You may select fixed spotsizes or use a rough approximation for
the intensities, which is Intensity is proportional to the
inverse of the internal space component of the diffraction vector.
[spot radii ~1/qi]