I have read about an electron making a transition between two energy levels and electromagnatic radiation will be emitted. The problem is how and why e.m radiation is emitted.
Answer
When we are calculating the energy levels of an atom (or anything else) we are generally solving the Schrodinger equation to calculate the energy eigenstates. These eigenstates have the property that they are time independant i.e. they do not change with time. So if you consider the ground state and an excited state we end up with the surprising result that since they are both time independant there can be no transition between them.
This is perfectly true, but only as long as we are considering the atom in isolation. If we introduce a photon then the electric field of the photon changes the Schrodinger equation so that the ground state and the excited state that we calculated above are no longer solutions. In that case the excited state gets mixed up with the combined system of the ground state plus a photon and there is now a non-zero probability that the excited state will decay. We calculate this probability using Fermi's golden rule.
To understand exactly how the transition happens requires quantum field theory because it involves the creation of a new particle (the photon) and particle creation is not described by non-relativistic quantum mechanics. Basically the energy of the excited state is transferred to the photon quantum field where the energy appears as the creation of a photon.
No comments:
Post a Comment