Consider the following case: An atom of hydrogen is in its ground state in vacuum. A single photon of light whose energy equals to the transition energy from the ground state( n=1) to the next energy level(n=2) is bombarded onto the atom. Now because the energy of the photon is same as that of the energy of the transition energy, the electron in the ground state will move to the next higher energy level. This is known as absorption. But because the total energy of the atom is higher it would want to go to a lower energy level. This is known as spontaneous emission. But the photon released in spontaneous emission is different from the photon initially bombarded( polarization, phase etc) but will have the same frequency.
So here’s my question:
- Why does the emitted photon differ from the incoming photon?
- In laser the excited electron when bombarded with an photon emits 2 photons which have the same properties of the incoming photon. Why are the properties of the incoming photon and the outgoing photons the same?