I am a high school student trying to understand how laser cooling works.
What I understand so far is that scientist take a bunch of atoms in vacuum and point lasers at them from all directions. The atoms will absorb the photons but only if they have a specific frequency that matches the one of the atom since an atom will only absorb a particle that has enough energy to transfer it to a higher energy level. I also understand that if an atom absorbs a photon moving in the same direction of it the atom will increase in velocity (meaning an increase in temperature which is opposite the desired effect) so to ensure that only atoms moving in the opposite direction of the photons absorbs them scientists take advantage of the doppler effect, so they tune the laser beam at a frequency slightly lower than the one the atom desires so that the atoms moving towards the photons see them as perfect frequency and absorbs them and the ones moving away see tham at lower frequency and therefore do not absorb them. All of this makes sense to me, however I do not understand what happens after that. I know that the atoms will return to their ground levels after reaching an excited state and will release a photon (in a random direction) of the same energy as the one it absorbed but what happens then?