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X-ray diffraction or reflection?

by sreerajt
Tags: diffraction, reflection, xray
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sreerajt
#1
Dec24-13, 08:29 PM
P: 28
In x-ray diffraction , even though its reflection is happening , we call this as x ray diffraction. why is it so?? i don't know whether it has been discussed previously here.
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TumblingDice
#2
Dec24-13, 09:05 PM
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Quote Quote by sreerajt View Post
In x-ray diffraction , even though its reflection is happening , we call this as x ray diffraction. why is it so?? i don't know whether it has been discussed previously here.
Actually its diffraction that's happening. The terminology 'reflections' applies to the spots/patterns generated when x-rays diffract through a set of evenly spaced planes in a crystal. It's the mathematics of the monochromatic frequency of the x-rays and the angle of diffraction as the crystal is rotated. Diffraction patterns of spots/reflections are generated when the resulting wave patterns coincide and support each other.
sreerajt
#3
Dec30-13, 10:41 PM
P: 28
does anybody have any other answer????

M Quack
#4
Dec31-13, 02:37 AM
P: 673
X-ray diffraction or reflection?

Reflection and diffraction are really two different aspects of the same thing. The term reflection is used mostly for what happens at the surface of a homogenous medium. This does occur for x-rays, but only at very small angles, because the index of refractions is very very close to 1. Nevertheless the effect is used for things like space-based x-ray telescopes, focusing and harmonic rejection of synchrotron radiation, etc.

http://en.wikipedia.org/wiki/X-ray_optics#Reflection

Diffraction relies on the (constructive) interference of wavelets scattered from a period arrangement of objects. For x-rays that can be a crystal lattice, an artificial multilayer, a Fresnel lens structure, etc. Diffraction does not necessarily happen at a surface. In fact, Max von Laue and coworkers first discovered x-ray diffraction in a transmission geometry.

http://www.iucr.org/__data/assets/pd.../721/chap4.pdf, near page 40.
TumblingDice
#5
Jan1-14, 08:05 PM
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Quote Quote by sreerajt View Post
does anybody have any other answer????
M Quack added good info and links for reflection and diffraction.

Here's another wiki link directly to X-ray Crystallography:
http://en.wikipedia.org/wiki/X-ray_crystallography

The link has some more good stuff that directly addresses your question regarding, "why":
In an X-ray diffraction measurement, a crystal is mounted on a goniometer and gradually rotated while being bombarded with X-rays, producing a diffraction pattern of regularly spaced spots known as reflections.
sreerajt
#6
Jan2-14, 08:01 PM
P: 28
Quote Quote by TumblingDice View Post
M Quack added good info and links for reflection and diffraction.

Here's another wiki link directly to X-ray Crystallography:
http://en.wikipedia.org/wiki/X-ray_crystallography

The link has some more good stuff that directly addresses your question regarding, "why":
You (actually Wikipedia ) are telling is that reflection ".... producing a diffraction pattern of regularly spaced spots known as reflections". But reflection is a physical phenomenon, so how cold you term spots as reflection??
M Quack
#7
Jan3-14, 01:36 AM
P: 673
That is just nomenclature. At the Bragg condition the crystal "reflects" (should be diffracts!) x-rays, that's why it is known as Bragg reflection. This is the term that everybody uses, and I do not know of any better term. Get used to it.
sreerajt
#8
Jan4-14, 03:14 AM
P: 28
Okay.. Thank you.....


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