Question

Electric dipole and magnetic dipole transition

Answer 1

Electric and magnetic dipole transition rates are first perturbation approximations. Perhaps this name is not very good because it can be confused with the idea of classical electric and magnetic dipoles. What is important to remark is that the electromagnetic radiation emitted or absorbed by an atom have transitions forbidden between certain atomic states which basically are obtained using Clebsch-Gordan coefficients in this first approach of the electromagnetic field. Let me to put the fundamental:

1. The transition rates are zero unless the difference between m initial and the m final is -1,0,+1.

2. In the same form the orbital momenta have to lf-li=-1,0,+1.

3. Finally, lf-li= odd integer

This means that , in the case of electric dipole transitions, the final and initial states must have different parities. For instance transitions like

1s to 2s

2p to 3p etc

are forbidden, while transitions

1s to 2p

2p to 3s etc

are allowed.

In contrast magnetic dipole transitions and quadrupole couple states with the same parity. A good book for seeing this topic is :

D.Griffiths, Introduction to Quantum Mechanics, Prentice-Hall,1995.

Answer 2

Answer:

Electric dipole transitions only have a non-vanishing matrix element between quantum states with different parity. Magnetic dipole transitions and electric quadrupole transitions in contrast couple states with the same parity.