Why energy level transitions only absorb or emit photons?

In summary, the conversation discusses the question of why energy level transitions of atoms can only emit massless photons and not other particles with mass. It is explained that this is due to the nature of the atom and the fact that emission of an electron would result in ionization. The conversation also touches upon the possibility of two different processes occurring during an energy level transition and what determines which one actually happens.
  • #1
arielleon
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The question occurred to me when I was thinking about black radiation. It is critically depend on the fact that the photon number is variable. Therefore I wonder why energy level transitions of atoms can only emit out the massless photons, but not any other kind of particles, even some with mass? It may be a stupid question, forgive me...
 
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  • #2
In most situations (electron transitions) there isn't enough energy to create a particle. In the case of nuclear transitions, particles (alpha, beta, neutrinos) are often emitted.
 
  • #3
And even the energy from electron transitions can be used to emit particles with mass, as is the case with http://en.wikipedia.org/wiki/Auger_effect" [Broken] for exampe, where the large energy from an electron falling into an inner core shell is enough to knock another electron out.
 
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  • #4
arielleon said:
The question occurred to me when I was thinking about black radiation. It is critically depend on the fact that the photon number is variable. Therefore I wonder why energy level transitions of atoms can only emit out the massless photons, but not any other kind of particles, even some with mass? It may be a stupid question, forgive me...

A transition from one energy level to another one must prevail the nature of the atom. Emission of an electron for instance would create a charged object instead of an atom; this process is called ionization.
 
  • #5
I see that the electron transition energy is too small to create particles with mass. Then I think of another question. If there're two atoms, one of which has an electron in excited state. Two kinds of processes are possible under the condition of the conservations of momentum and energy: the transition energy all becomes the kinetic energy, or emit a photon. Then what determines the actual case, or the possibility of each case? Thx.
 

1. Why do energy level transitions only absorb or emit photons?

The energy level transitions in an atom occur when an electron moves from one energy level to another. This movement is accompanied by the absorption or emission of a photon, which is a packet of electromagnetic energy. This is due to the fact that the energy levels in an atom are discrete, meaning they can only have specific values. When an electron moves between these levels, it can only gain or lose energy in specific amounts, which corresponds to the energy of a photon.

2. Can energy level transitions emit or absorb other forms of energy besides photons?

No, energy level transitions in an atom can only emit or absorb photons. This is because photons are the only carriers of electromagnetic energy, and the energy levels in an atom are specifically related to the electromagnetic force. Other forms of energy, such as thermal or kinetic energy, cannot be emitted or absorbed by energy level transitions.

3. How does the energy of a photon relate to the energy level transitions in an atom?

The energy of a photon is directly related to the energy difference between the two energy levels involved in the transition. The higher the energy difference, the higher the energy of the photon emitted or absorbed. This relationship is described by the equation E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency of the photon.

4. Why do energy level transitions occur at specific wavelengths?

The specific wavelengths at which energy level transitions occur are determined by the energy difference between the two levels. This energy difference corresponds to a specific frequency and wavelength of the photon that is emitted or absorbed. This is why different atoms have different characteristic emission or absorption spectra, as the energy levels in each atom are unique and result in different energy differences and corresponding wavelengths.

5. Is it possible for energy level transitions to occur without the emission or absorption of a photon?

No, energy level transitions cannot occur without the emission or absorption of a photon. This is because the energy levels in an atom are quantized, meaning they can only have specific values. When an electron moves between these levels, it must either gain or lose energy in specific amounts, which corresponds to the energy of a photon. Therefore, energy level transitions are always accompanied by the emission or absorption of a photon.

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