Do just electrons emit photons?

  • #51
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ignoring the answers (not just mine but several others)

Acknowledging those answers that were, in fact, very helpful, and complementing the authors in the process, is hardly ignoring 'the answers'.

does concern me that you would assume that it only requires a bit of time

I never said that it requires a bit of time.

And, again, just to clarify, I wasn't speaking of an isolated molecule a while back. I was merely trying to understand the correct terminology to use when describing the whole system (without just saying 'whole system') that radiates blackbody radiation (which is a very good question, by the way).

If someone would like to answer that question properly, and simply, I believe I would be capable of understanding it. DrClaude gave a great answer, but it pertained to the isolated atoms and molecules. ZapperZ gave a great answer, but not sure if he meant the vibrational modes/phonons, only, as the cause to the blackbody radiation. From what I've been studying since, it looks like that may be only part of it (the vibrational modes). And, as for you, you've thought I've been referring to an isolated molecule all along when I haven't.

I am, in fact, talking about the entire system of an object and how to properly sum up what it is that's causing the radiation (lattice vibrations, an aggregate of the molecular vibrations, or a combination of both)? And to be honest, there just aren't sufficient answers on the Internet. So, I agree, a textbook would be of better help. When I have a good amount of time, I will be putting a lot more into this. But, in the meantime, it was just a question based on true, earnest study given the time and material at hand. That's all. A question.

I'm not asking for the world. I was just asking something pertaining to a particular area (and, yes, I realize the area as a whole will take a lot more time to understand). And I'm asking that you try to see that I was never talking about an isolated molecule.
 
  • #52
PeterDonis
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I was merely trying to understand the correct terminology to use when describing the whole system (without just saying 'whole system') that radiates blackbody radiation (which is a very good question, by the way).

The correct terminology to use, at the level of detail you're asking for in this thread, is that the whole system radiates blackbody radiation.

I am, in fact, talking about the entire system of an object and how to properly sum up what it is that's causing the radiation (lattice vibrations, an aggregate of the molecular vibrations, or a combination of both)?

A combination of both, plus a lot of other stuff, all of which can only be summed up in simple terms by saying "the whole system". Until you put in the time to study the subject in detail, that's really the best answer that you can get.
 
  • #53
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For example, the answer to the title question of this thread, as you ask it, is simple: "No." But the reason the answer is "no" is not that, oh, there isn't just one kind of thing that can emit photons (electrons), but three or four (electrons, molecular vibrations, rotations, ...).

I just saw your answer after typing my last post. Thank you. -- Both answers. I will go over what you just posted. Again, thank you.
 
  • #54
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A combination of both, plus a lot of other stuff, all of which can only be summed up in simple terms by saying "the whole system". Until you put in the time to study the subject in detail, that's really the best answer that you can get.

Thanks so much. I had a feeling it was more than just vibrational modes. And, as for the molecular vibrations, when I was speaking of those types of vibrations in the past, on this thread, I meant as an aggregate -- a whole. I never meant to give the impression that I was looking at it as an individual concept.

But I really appreciate your answer. And I am aware that I have a lot to study. Just hope to find the "right" books.
 
  • #57
Hi desta41,

I am not surprised you are confused. Most of the answers you have got are misleading!

There are two types of radiation - continuum and line. Blackbody radiation is of the continuum type and the radiation produced by an electron changing state in a hydrogen atom is line radiation. Another type of continuum radaition is Bremsstralung (braking radiation). It is produced when an (high powered) electron hits an atom and is slowed as it approaches the positively charged nucleus. The loss of energy is converted into contnuum radiation. IMHO, blackbody radiation is produced by the vibrations in a solid causing the free electrons to bounce off the nucleii of the atoms, so producing continuum radiation in a similar fashion.

The classic line radiation is produced by the electron in an atom jumping from one quantum state to another, either as the result of absorbing the energy of a photon, or spontaneously and emitting a photon equal to its loss of energy. That is at a fairly high energies so only occurs as visible light.

Molecules can also absorb and emit photons, but only if their rotations and/or vibrations cause their overall electromagnetic field to be distorted. Note that from this POV the electron is a cloud, not a particle, surrounging the nucleus. The energy levels of vibrations is in the infra red (IR). A hydrogen molecule does not have a distoted emf i.e. it does not have a dipole and is not IR active. When it vibrates, i..e. strtches, the emf remains symetrical, similarly for oxygen and nitrogen molecules. But when carbon dioxide vibrates it does create distorted field. The oxygen bonds can waggle and they can stretch asymetrically, and so it acts as a greenhouse gas.

It is all a matter of quantum mechanics, but it is not simple.

HTH,

Cheers, Alastair.
 
  • #58
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Another type of continuum radaition is Bremsstralung (braking radiation). It is produced when an (high powered) electron hits an atom and is slowed as it approaches the positively charged nucleus.

I remember studying up on braking radiation. I appreciate your putting this into perspective for when it comes to continuum radiation.

Molecules can also absorb and emit photons, but only if their rotations and/or vibrations cause their overall electromagnetic field to be distorted. Note that from this POV the electron is a cloud, not a particle, surrounging the nucleus. The energy levels of vibrations is in the infra red (IR). A hydrogen molecule does not have a distoted emf i.e. it does not have a dipole and is not IR active. When it vibrates, i..e. strtches, the emf remains symetrical, similarly for oxygen and nitrogen molecules. But when carbon dioxide vibrates it does create distorted field. The oxygen bonds can waggle and they can stretch asymetrically, and so it acts as a greenhouse gas.

Very clearly stated, and makes sense. Thank you for taking the time.
 
  • #59
ZapperZ
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Wait till you visit a synchrotron light source or an FEL and see how such a facility generate light. You'll see why my claim of shaking charge up and down is relevant.

Zz.
 
  • #60
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Synchrotron radiation from accelerated protons is a significant issue in the LHC.
 
  • #61
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You'll see why my claim of shaking charge up and down is relevant

I absolutely hear you
 
  • #62
When atoms and molecules are clumped together into a solid, they form a conglomerate in which the characteristics of the solid are predominately due to the collective behavior of all these atoms and molecules. What that means is that the individual behavior of the atoms and molecules are often no longer apparent in the properties of the solids.

Is radio frequency emission from a wire antenna an example of the type of collective behavior you refer to? I ask because I have not been able to find a description of antenna behavior, whether transmitting or receiving, from a quantum viewpoint. Everything about antennas seems to be discussed from a purely classical EM perspective. I don't doubt that this is the right practical approach, but I would like to see some kind of quantum treatment, if only a simple-minded description of the process by which photons are emitted from the wire.
 
  • #63
ZapperZ
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Is radio frequency emission from a wire antenna an example of the type of collective behavior you refer to? I ask because I have not been able to find a description of antenna behavior, whether transmitting or receiving, from a quantum viewpoint. Everything about antennas seems to be discussed from a purely classical EM perspective. I don't doubt that this is the right practical approach, but I would like to see some kind of quantum treatment, if only a simple-minded description of the process by which photons are emitted from the wire.

No, it is not. An antenna is described in classical E&M and a boundary condition problem. However, it shares similarities with the jiggling charge that I mentioned.

Zz.
 
  • #64
PeterDonis
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I would like to see some kind of quantum treatment, if only a simple-minded description of the process by which photons are emitted from the wire.

You're assuming that the EM field in question can be usefully modeled as "photons emitted from the wire". As I understand it, the EM wave state that is emitted is very different from the kinds of EM states that the term "photon" can be usefully applied to. (For one thing, AFAIK the wave state is not an eigenstate of the photon number operator.)
 

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