For a full answer to all your questions, I refer you to the classic
textbook of M. M. Woolfson an introduction to x-ray crystallography by
Cambridge University Press. This book has been quite helpful to me of
late. Unlike some similar texts I find it easy to read. There are even
examples!
] Questions about diffraction
For a full answer to all your questions, I refer you to the classic
textbook of M. M. Woolfson an introduction to x-ray crystallography by
Cambridge University Press. This book has been quite helpful to me of
late. Unlike some similar texts I find it easy to read
On Friday 24 August 2007 12:22, Michel Fodje wrote:
1. In every description of Braggs' law I've seen, the in-coming waves
have to be in phase. Why is that? Given that the sources used for
diffraction studies are mostly non-coherent.
Think of Bragg's Law as explaining what happens to a single
Michel Fodje wrote:
Dear Crystallographers,
Here are a few paradoxes about diffraction I would like to get some
answers about:
...
3. What happens to the photon energy when waves destructively interfere
as mentioned in the text books. Doesn't 'destructive interference'
appear to violate the
1. In every description of Braggs' law I've seen, the in-coming waves
have to be in phase. Why is that? Given that the sources used for
diffraction studies are mostly non-coherent.
Think of Bragg's Law as explaining what happens to a single photon
that is probabilistically scattered by
For every direction where there is destructive interference and a
loss of energy there is a direction where there is constructive
interference that piles up energy. If you integrate over all
directions
energy is conserved.
For the total integrated energy to be conserved, energy will have to
You are just using the coherent fraction of the beam.
My point is that Braggs' law as currently understood does not preclude
the diffraction from waves which were non-coherent before hitting the
sample
It is not clear at all how you arrive to that condition. By definition, if
two waves are non
For the total integrated energy to be conserved, energy will have to be
created in certain directions to compensate for the loss in other
directions. So in a direction in which the condition is met, the total
will have to be more than the sum of the waves in that direction.
How about considering
On Fri, 24 Aug 2007 14:40:13 -0600
Michel Fodje [EMAIL PROTECTED] wrote:
The mathematics works but doesn't necessarily mean the current
interpretation of the mathematics has any resemblance to what actually
happens in reality.
Sure, it does. Crystallography is traditionally
Michel Fodje wrote:
For every direction where there is destructive interference and a
loss of energy there is a direction where there is constructive
interference that piles up energy. If you integrate over all directions
energy is conserved.
For the total integrated energy to be conserved,
Here's a fun way to think of it:
A photon hits a crystal and will diffract off in a certain direction
with the same energy as the original photon. The direction is subject to
a probability distribution based on the lattice, with angles at the
diffraction conditions being most likely and the
Without resorting to a circular argument? You are asking too much.
However, this probability distribution is perfectly described by
considering a component wave model wherein coherence of the component
waves correlates with peaks in the probability distribution--i.e.
Bragg's Law.
IANAM (I
Would it be taking it too far to suggest that one could go all the way
and consider that each electron diffracts not as groups in a plane but
as individual electrons and a photon impinging on an electron with with
a specific phase will be diffracted in a specific direction. However the
lattice
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