Zeeman Effect Theory

1847 Words8 Pages
It is a known fact that atoms have quantised energies, that is, they can only have a discrete set of energy values. When irradiated by electromagnetic radiation, atoms absorb certain frequencies from the radiation thus transitioning between energy levels. If the incident radiation is compared with the one coming from the atoms, a continuous spectrum can be observed with frequencies matching those between the energy levels missing. The spectrum is unique to the element and displays the fact that the energy levels are quantised. In the presence of a magnet field the energy levels of the atom split, and the spectral lines are split into several parts. This is the called Zeeman effect.

Physicist Pieter Zeeman discovered the effect and hence its
…show more content…
Many other elements were observed to have three or more splits in their spectral lines that increased very fast with increase in field strength. This went against the initial classical explanation suggested by Lorentz. The effect was termed the anomalous Zeeman Effect for such elements. The Stern-Gerlach experiment in 1922 further proved that the classical explanation failed to fully explain the Zeeman Effect. A beam of collimated silver atoms was fired through a non-uniform magnetic field. The beam had split into two parts, one going up the z-axis and the other down the z-axis, where the z-axis is the axis of the magnetic field. The observed bifurcation was inconsistent with the present explanation as angular momentum had integer values. Other elements also had more than two parts in the experiment. The results proved that atomic space was quantised since only the readings for the magnetic dipole moment in the arbitrary z direction only took certain discrete values. The values of the dipole moment were not the same as those predicted by equation (5). One thought was that the discrepancy was due to the magnetic dipole of nucleons, but since the values were of the order of the Bohr magneton which is about 2000 times more than those expected from the nucleus the thought was ruled…show more content…
The Stark effect followed the Zeeman effect. It is a similar concept to the Zeeman effect but about the influence of electric field on the spectral line. One application of the Zeeman effect has been in laser cooling and trapping. The idea is that since temperature of a substance is related to the distribution of speed of the atoms in the substance, then by slowing down the atoms the substance can be cooled. The atoms are slowed down my photons using the conservation of momentum. The photons are at lower energies than needed by the atoms for energy transitions. When the photon and atom are moving towards each other the energy of the photon looks more like the one needed for transitioning because of the doppler effect. The slowing down happens after many absorb and release actions by the atom, thereby losing momentum. Introduction of a varying magnetic field will shift the energy levels of the atom making it more probable for them to absorb the photons. The Zeeman effect has also been observed in astrophysics. In 1908, George E. Hale discovered that the effect in the sun. He noted that the sunspots had a magnetic nature and formulated polarisation laws for the
Open Document