Photons (compton effect, pair production)

[~()]

How can a photon knock an electron from a shell, entirely out of the atom?
(i.e PhotoElectric Effect)

Photons have 0 rest mass, and little relativistic mass?

For force, F = ma

For example, let m = negligable (like the photon's mass is) mass so = mn

If F = (mn)a and mn is small, then no matter how fast the acceleration, in this case c = 3.0*10^8ms-1, Force will still be negligable.

Yes, it is true that you cannot use classical mechanics and apply it directly to quantum physics, in this case it would be better to use relatavisitic calculations, but most formula's in QM were developed from classical motion formulas. Just take the bohr radius for example, its a contruction centripetal acceleration (classical circular motion), F = ma is even interpolated in it, Couloms Law and other formula's. This gives the bohr radius 0.0529 * 10^ -10m

I propose that an electron can only absorb or reflect a photon...
If it absorbs the photon, the electron will go into an exicted state, i.e its energy will be greater, and it will leave the discrete quantised energy level which requires the electrons to be at a certain energy.

Both wavefunctions for electrons and photons are on the scale of nano meters or 10^-10 m. Is there a correllation between the W0 (work function) proposed by Einstien, - i.e the minimum energy needed to knock an electron out of an atom, and the wavelength of an electron in a particular energy level to the wavelength of the incident photon that has W0?
Maybe wavefunctions of the same frequency or wavelength determine wheter a photon is absorbed or reflected?

And why do we talk of photons as is they are comparable in anyway to a fermion or hadron? Like when we say when an electron jumps from a higher shell to a lower shell, it will emit one red photon for example.

 

[ZapperZ]

There are so many things that are wrong in here, I don't even know where to start.

1. You must have slept through the class when Special Relativity was being taught. Photons have MOMENTUM. Now it is up to you to go look up how it can have a momentum but no rest mass.

2. A photoelectric effect is done on SOLIDS such as metals. The conduction electrons are the ones typically involved in such a process. These electrons are not tired to any atom, but rather to the band structure of the metal. There are no photoionization involved.

3. A photon isn't "absorbed" by an electron. This is impossible since it violates several conservation rules.

4. A photon, however, CAN be absorbed by the whole atom, or the solid. The energy level that we all love is the result of WHOLE system, not just the electron (look at the Hamiltonian if you don't believe me). The atom, or solid, absorbs the photon, causing a transition.

5. The work function has nothing to do with the photon. It has everything to do with the property of the material itself. It doesn't even have anything directly to do with the individual atoms in the material.

Someone else can tackle the rest.

Zz.

 

[denian]

I can understand your confusion and questions about how a photon can knock an electron out of an atom and the relationship between the two. Let's start by clarifying a few things.

Firstly, photons are particles of light that have both wave-like and particle-like properties. They have zero rest mass, but they do have energy and momentum. The energy of a photon is directly proportional to its frequency, while its momentum is inversely proportional to its wavelength. This is described by the famous equation E=hf, where h is Planck's constant and f is the frequency of the photon.

Now, when a photon interacts with an electron in an atom, it can transfer its energy and momentum to the electron. This can happen in two ways: the photoelectric effect and the Compton effect.

In the photoelectric effect, the photon transfers all of its energy to the electron, knocking it out of the atom. This happens when the energy of the photon is equal to or greater than the work function of the material. The work function is the minimum amount of energy needed to remove an electron from the surface of a material. So, in this case, the wavelength of the photon does not play a role in knocking the electron out of the atom.

In the Compton effect, the photon transfers some of its energy to the electron, causing it to recoil. This happens when the energy of the photon is lower than the work function. In this case, the wavelength of the photon does play a role, as it determines the amount of energy and momentum that the electron will receive.

As for the relationship between the wavelength of the photon and the energy level of the electron, there is indeed a correlation. The energy levels of electrons in an atom are quantized, meaning they can only exist at certain discrete energy levels. The wavelength of the photon needed to move an electron from one energy level to another is determined by the energy difference between the two levels.

Finally, photons are not comparable to fermions or hadrons, as they are not particles that make up matter. They are fundamental particles that carry energy and interact with matter through electromagnetic forces. When we talk about an electron emitting a photon, it is simply a way of describing the energy transition that occurs as the electron moves from a higher energy level to a lower one.

I hope this helps to clarify some of your questions and demonstrates the complex yet fascinating nature of photons and their interactions with matter.