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What is the difference between coherent and elastic scattering. Maybe the elastic scattering implies that there is not loss of energy, whereas the coherent scattering implies that the wavelength of a beam is the same before and after the scattering?

Thank you in advance.

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    $\begingroup$ could you elaborate the context . For all practical purposes elastic scattering would mean no energy loss and coherence implies constant phase difference with frequency . In atomic level particles behave as waves and tend to be coherent . Since mass is negligible collisions are generally elastic . $\endgroup$ – shrey Dec 9 '16 at 12:45
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This is related to a fundamental misunderstanding of coherence (which is very common). Coherent processes are typically associated with wave coherence, so coherent scattering means scattering of two waves. This is in opposition with scattering between a wave and something that is not a wave (or, by some interpretations, something that does not behave like a wave, like a macroscopic bunch of matter such as a bouncing ball).

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  • $\begingroup$ Coherent applies to particles as well as waves. A wave of soldiers marching in step is analogous to a flux of coherent photons. They resemble a wave but are all individual, moving in phase at the same speed and frequency. $\endgroup$ – Bill Alsept Dec 10 '18 at 5:56
  • $\begingroup$ coherence is inherently a wave property. In the particular case you mentioned, what matters is why the phase relation between soldiers goes away. Importantly, when your system is reduced to only one soldier-wave, your description breaks down, hence my comment. $\endgroup$ – Peter James Beierle Dec 10 '18 at 6:33
  • $\begingroup$ there could never be a one soldier-wave or a a single photon wave. My point is that there wouldn’t be waves without particles. If light waves are not made of billions individual photons, what then? $\endgroup$ – Bill Alsept Dec 10 '18 at 7:14
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First need to understand that when comparing Coherent scattering and elastic scattering refers to a wave that has been absorbed follow by a re-emission at the same frequency of the incident wave. The coherent means that the re-emission of the wave maintains the same direction of the incident ray (like laser beams). Elastic scattering is any other new re-emission but traveling in a different direction.

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