To be used in future
Prev Section 4.4: Landau Levels
Up Chapter 4: Charged Particles and Electromagnetic Fields
Section 4.6: Internal degrees of freedom: spin Next
4.5 Coupling of light to atoms and nuclei: multipole couplings
If we consider light fields of wavelength much larger than the atom; also consider classical fields (we know we should quantise, since fields contain photons). Really geared towards the use of Fermi-Golden rule type calculations.
For the scalar potential we can make a multipole expansion
We assume the fields are weak, so we can perform a first order perturbation theory. The matrix elements we need to calculate are of the form
In atoms we find that the dominant term is
, this is linked to the strong dipole matrix elements in atoms,
These are also called
(electric,
) transitions.
In atomic nuclei we can’t have large dipoles (why?), but we often large quadrupole, so
Selection rules (parity)
Magnetic couplings (in expansion of
, much more complicated).
Particle in laser fields: sytrong dipole interaction
This work is a Open Educational Resource. Please contact Niels Walet for more information, or further licensing.
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Generic License