# X-ray diffraction or reflection?

by sreerajt
Tags: diffraction, reflection, xray
 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.
PF Gold
P: 187
 Quote by sreerajt 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.
 P: 28 does anybody have any other answer????
P: 627

## 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.
PF Gold
P: 187
 Quote by sreerajt does anybody have any other answer????

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