Zeeman Effect Simulation

Theoretical Background / Context

• The splitting of the Cd-spectral line λ = 643.8 nm into three lines, the so-called Lorentz triplets, occurs since the Cd-atom represents a singlet system of total spin S = 0. In the absence of a magnetic field there is only one possible transition of 643.8 nm,

  1D2 (J = 2, S = 0)    →  1P1 (J = 1, S = 0)            

• In the presence of a magnetic field the associated energy levels split into 2 J + 1 components. Radiating transitions between these components are possible, provided that the selection rules

ΔMJ = +1;         ΔMJ = 0;          ΔMJ = –1

are taken into account. In this case, therefore, there are a total of nine permitted transitions, only three of which ever have the same energy and hence the same wavelength. Therefore, only three lines will be visible.

Principle of Work

• In zeeman effect experiment, When the cadmium lamp was turned on, the light emitted passed through a condensing lens, such that it was approximately parallel, then through the  Fabry-Perot etalon, an imaging lens with a known focal length (in this case, 150 mm).
• Finally, the light passed through a red-colored filter. Although it is possible to use an ocular to observe the ring pattern directly, a CCD camera is used later in the zeeman effect experiment. Both the camera and ocular were positioned at the focal point of the lens.
• The data from the CCD was transferred to a computer via USB for analysis.

• Additionally, a quarter-wave plate, polarizing filter or both can be positioned in front of the etalon.