This article was registered in the quality assurance of the physics editorial team . If you are familiar with the topic, you are welcome to participate in the review and possible improvement of the article. The exchange of views about this is currently not taking place on the article discussion page , but on the quality assurance side of physics.
Electrons are bound to the atomic nucleus analogously to springs of different strengths ( anisotropy )
The dynamics of electrons, ions or permanent dipoles in a solid can be described in a simplified way by a damped harmonic oscillator . The following equation of motion is set up for electrons without loss of generality . Analog equations can be set up for ions and permanent dipoles. As a model, one can imagine that the electrons in the atomic shell are attached to the atomic nucleus with springs in the Lorentz model. If the springs of all electrons have the same spring constant, that would correspond to an isotropic medium. The periodic driving force is the interaction with a monochromatic electromagnetic alternating field , e.g. B. light, radio or microwave , a:
: local amplitude of the driving electromagnetic alternating field
The stationary solution of this equation of motion is:
application
Atomic dipole moment
The atomic dipole moment is defined as , where from the electron points to the nucleus, so that this is to
results.
Dielectric function
Real and imaginary part of the dielectric function depending on the angular frequency of the driving field
Real and imaginary part of the dielectric function in the visual area for a semiconductor ( silicon ) with band transitions in this area; in contrast to the picture above, the horiz. Axis the wavelength plotted
Real materials always have more than just one resonance frequency , as several electronic transitions exist; each of them makes a contribution to the electronic polarizability according to its oscillator strength
In the case of solids, the splitting into energy bands ( band structure ) plays an important role with regard to the possible transitions.