Spontaneous emission is understood as the process of spontaneous emission of electromagnetic radiation by quantum systems (atoms, molecules) during their transition from an excited state to a stable state.
This is approximately how Wikipedia interprets spontaneous emission, and, of course, the entire scientific community. Scientists reason about the cause of spontaneous emission as follows:
“The process of spontaneous emission cannot be explained from the point of view of the positions of the original version of quantum mechanics, where there was a quantization of the energy levels of the atom, but there was no quantization of the electromagnetic field. Excited states of atoms are exact stationary solutions of the Schrodinger equation. Thus, atoms must remain in an excited state indefinitely. The cause of spontaneous emission is the interaction of an atom with zero-point oscillations of the electromagnetic field in vacuum. The states of the atom cease to be stationary as a result of the action of the component of zero-point vibrations with a frequency equal to the frequency of the emitted quantum. ”
As you can see, science believes that spontaneous radiation is a spontaneous action, but still not too spontaneous, because it requires external zero-point oscillations of the electromagnetic field in a vacuum. Do not be for these zero fluctuations and spontaneous actions come to an end. And most importantly, they save Schrodinger's theory. If these zero-point vibrations did not exist, then all the excited states of the atoms would obviously be stationary. And the current stationary states would become even more stationary. Why is it so gibberish? It's very simple. There is no more or less decent model of an atom and a photon.
You can work with the Schrodinger model only outside the boundaries of sound logic, whither to scientists have introduced quantum mechanics, with virtual mathematical images that exist only in the minds of scientists. Obviously, there is none of this in nature.
We have to work with Bohr's model, but it is not convincing. I don’t know why, but when constructing a model of the atom, only the forces of attraction between the nucleus and the electron, the inertia of the electron and the quantum ability to emit and absorb a quantum by the accelerating electron Why was the magnetic component of the nucleus not taken into account?
Didn't know and don't know anything about Kaufman's experiments ? Yes, a moving electron cannot fall on the nucleus in any way. There is a huge magnetic field near the nucleus, it will lead the electron to the side. The earth, thanks to its magnetic field, takes away a lot from direct hit on itself. How an atom works, taking into account the magnetic field of the nucleus, is described in the article The atom, its quantum device. From this point of view, we will look at the process of spontaneous emission.
At point 1, the forces of the photon (previously reflected) and the electric field of the nucleus pull the electron to the nucleus, accelerate it and make it emit the absorbed photon back, and the magnetic field of the nucleus is constantly trying to change the trajectory of the electron to the side. At point 2, only an electric force of attraction acts on the electron, since the photon was absorbed at point 1, and if there were no other forces, then the electron would fly directly by inertia. And at the same time, at point 2, the magnetic field increased (closer to the nucleus, the magnetic field increases), which sent the electron to point 3.
At point 3, the process is repeated, and so on. If the parameters of the forces, and especially the photon, are such that the electron, after all the cycles of its flight around the nucleus, will again fall strictly to point 1 (Fig. 4)
Quantum is about 1/10 41 part of an electron. That is, the size of a quantum is much smaller than the size of an electron. A photon consists of quanta, and even if it contains a billion quanta, it will also be much smaller than an electron. The interaction of a photon and an electron occurs only when a photon, moving straight ahead, hits an electron or, say more carefully, into its effective cross section. This means that in a stationary orbit, a photon should not only fall into an electron, but also fall into the same place on it (Fig. 3a).
If the exchange photon hits the electron along the line а , then this connection between the nucleus and the electron will exist forever, naturally, in the absence of external disturbances. The path of the photon in the atom is 1- o -5, and the path of the electron is 1-2-3-4-5. The energy of the exchange photon depends to some extent on the mode of entry of the electron into point 1.
At point 1, certain electric and magnetic forces act, which, depending on the speed of the electron, will make it generate a photon of the corresponding energy. If the total time of generation (t rad ), propagation (2t spread ) and absorption (t absorption ) of a photon will be equal to the time of motion of an electron from point 1 to point 5, then the photon will hit the point а of the electron.
But it may happen that with a slightly different input speed of the electron to point 1, the same forces will form a photon of a different energy: more or less energy, in contrast to the nominal, at which it hits the point a . In this case, the generation and absorption times will be more or less than the nominal times. It may turn out that the time of movement of a photon from 1 to 5 will be slightly more or less than the time of movement of an electron from point 1 to point 5. In these cases, the point of meeting of the photon and the electron will shift on the electron towards the line os or the line ob .
The more the exchange photon differs in energy from the nominal photon, the further the interaction point moves along the electron from the point а . This shift occurs by the same amount in each exchange cycle. How many such electron exchange cycles we do not know, especially in many electron atoms.
With each revolution of the electron, the shift is increasing and increasing, and, in the end, there comes a moment when the photon will fly past the electron without interacting with it. This is the act of spontaneous emission of a photon by an atom. Such radiation is not provoked by anything from the outside and it seems to us that the atom emitted a photon for no apparent reason.
There are many examples of such radiation. As Wikipedia writes:
1. Fluorescence - “This is a physical phenomenon, the essence of which is the short-term absorption of a quantum of light by a fluorophore (a substance capable of fluorescence), followed by rapid emission of a quantum, which has properties different from the original” .
In this article, we will not analyze the physics of this phenomenon, only note that the subsequent radiation occurs relatively quickly.
2. “Phosphorescence is a special type of photoluminescence. Unlike a fluorescent substance, a phosphorescent substance does not emit absorbed energy immediately. ”.
Here the radiation can last for several hours. What follows is a confusing explanation of why this is so.
There are many more types of such radiation: luminescence, chemiluminescence, bioluminescence, etc. Yes, a piece of iron heated to red spontaneously emits photons of the visible, infrared and other types of spectrum. Simple cooling of a body is a spontaneous emission of thermal photons. But nowhere is there a clear description of the physical nature of these phenomena.
If we consider these phenomena from the point of view of the quantum model of the atom, then everything becomes obvious. Moreover, it can be assumed that such quasi-stationary states of atoms are a very widespread phenomenon. If the exchange photon differs from the nominal photon by 1 quantum, then it is possible that this electron will exist at this level for millions or billions of years. It can be calculated, all data can be obtained.
Since after the emission of a photon, the electron goes to a faster level, that is, it is “pressed” closer to the nucleus, it can be assumed that this is how atoms were formed evolutionarily. This assumption is supported by the presence of ions.