Collision between photon and atom

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    Atom Collision Photon
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Discussion Overview

The discussion revolves around the nature of photon absorption in terms of collision classification, specifically whether it is an elastic or inelastic collision. Participants explore the definitions and conditions under which photon absorption might be categorized differently, including resonant and off-resonant conditions.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants suggest that photon absorption can be viewed as both elastic and inelastic depending on the conditions, particularly resonant versus off-resonant scenarios.
  • One participant argues that photon absorption is inherently inelastic, as it involves energy transfer from the photon to the absorbing atom.
  • Another viewpoint posits that if a photon of the same energy is emitted immediately after absorption, the overall process could be considered elastic, introducing a conditional aspect to the classification.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether photon absorption should be classified as elastic or inelastic, with multiple competing views remaining on the topic.

Contextual Notes

Definitions of elastic and inelastic collisions are debated, particularly in relation to energy transfer and the conditions of the absorption process. The discussion highlights the complexity of categorizing photon absorption without resolving the underlying assumptions.

kmarinas86
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Is photon absorption an elastic or inelastic collision? neither?
 
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Under resonant conditions you can look at the absorption process as an elastic scattering event and as an inelastic one while off resonance. On resonance it also dependends on what decay channels the excited electron has.
 
kmarinas86 said:
Is photon absorption an elastic or inelastic collision? neither?
The term "elastic collision" usually refers to a two-body scattering where each body has the same final energy in the center of mass system as its initial energy. With this definition, absorption is an inelastic process.
 
kmarinas86 said:
Is photon absorption an elastic or inelastic collision? neither?
If the photon is "absorbed" it means that its energy is totally or partially transferred to the absorbing system, so the process it's inelastic by definition. However, if another photon of the same energy is emitted immediately after the absorption, the overall process can be considered as elastic.
 

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