# Collision in the atom

by tsochiu
Tags: atom, collision
 P: 17 I have some difficulties in studying the part of collision in quantum physics. Will a photon with energy 5EJ collides with a electron with the ionization energy 4EJ in the non-metal atom? (E is a constant) Will a bombarding electron with kinetic energy 5EJ collides inelasticly with a electron with the ionization energy 4EJ in the atom? Will a bombarding electron with kinetic energy 5EJ collides inelasticly with a electron with the excitation energy 4EJ in the atom? Thanks a lot.
 Sci Advisor HW Helper P: 4,738 What do you mean by "collision" here? The classical view?
P: 17
 Quote by malawi_glenn What do you mean by "collision" here? The classical view?
You may see it as a way to transfer energy. I am not sure will the photon or electron "touch" each other.

 Sci Advisor HW Helper P: 4,738 Collision in the atom The photon and electron interacts via exchange of virtual photon, the force medatior of EM-force. This smells like a homework related question.
 Admin P: 21,887 Compare the energy of the incident photon/electron with the atomic binding energy and rest mass of the electron. This does seem like a homework problem. E is a constant? So EJ is not exajoule?
 P: 17 Excuse me, I found difficulties in understanding the physical terms as my teacher touches this topic recently. From my knowledge, to excite an electron from a certain obrital to another, we need a photon with energy exceptly the same as the excitation energy. Therefore, only light with certain wavelengths will be absorbed by an atom when passing through it. But I don't know what will happen in the situation of ionization, and will incident electron just do elastic collision if it's KE is too large. And..............I am afraid to said that my teacher's failed to answer me............. So, I seek help here, and thanks for saying that I am asking some good questions. So would you mind answer my question directly and give some explaination on it? Moreover, I just let a constant E to make the situation universal, as I don't know how large is the excitation/ionization energy. Thanks
 Sci Advisor HW Helper P: 4,738 in ionization, you must have an energy of the photon that is higher than the ionization energy of that perticular electron. The rest energy is then beeing kinetic energy to the electron. This is the photoelectric effect.
 P: 17 So how about the excitation with an incident electron?
 Sci Advisor HW Helper P: 4,738 Will a bombarding electron with kinetic energy 5EJ collides inelasticly with a electron with the ionization energy 4EJ in the atom? Will a bombarding electron with kinetic energy 5EJ collides inelasticly with a electron with the excitation energy 4EJ in the atom? Check the grammar. I cant see what you are looking for. The same things holds for the electron, just put up the equation for energy conservation. Now tell me what you want to calculate.. do you mean: Will a bombarding electron with kinetic energy 5EJ collide inelasticly with a electron with the ionization energy 4EJ in the atom? Will a bombarding electron with kinetic energy 5EJ collide inelasticly with a electron with the excitation energy 4EJ in the atom? Inelastic collision in this case is that the electron loses energy, i.e transfer energy to an atomic electron. Show your attempt do a solution, and in the future post homework/course work questions in the homework forum (this is an introductory physics assignment).
 P: 17 ...............You still think I am doing the homework.............. Actually, I am referring to the Franck-Hertz experiment. They have concluded from their experiment that the electrons in the atom only receive some except values of energy, for example, the excitation energy 4EJ . And in the case of photon, any photon with energy smaller or larger than that energy will just pass through. So, I am wondering will the incident electron with energy larger 4EJ "collide" with the atomic electron. Also in the case of ionization. And I do know what is the meaning of elastic collision, indeed, if any kinetic energy lost in the system, the collision is said to be inelastic. So as kinetic energy us transferred to poteinal energy in the atomic electron, the collision is said to be inelastic. I don't want to do the calculation, I just want to know what will happen as the collision between the atomic electron and incident electron is different from two free electrons. So, do I earn your trust now? If you still think I am doing homework, you may give me a related web page, as that is difficult to find either. Anyway, thank you.
 Sci Advisor HW Helper P: 4,738 An atom can be excited and ionized by "collisions" with electrons and other atoms.
 P: 17 Yes, also can be by the photons.

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