Splitting patterns Zeeman effect

Let us compare the spectral pattern of a Zeeman-split 1P-1S transition with the Zeeman effect on an electronic transition between an atomic singlet... 

The second diagnostic study made use of the Zeeman effect, observed when a small magnetic field was applied parallel to the ion beam direction. For almost every line in the spectrum a Zeeman splitting could be observed figure 10.73 illustrates a particularly simple example, where the six-line Zeeman pattern shows conclusively that the resonance must arise from a J = 3/2 3/2 transition. Effective g factors... 

The magnetic field strength and the direction cosines between the field and the molecular axis system enter linearly in the g term ( linear Zeeman effect contribution ). Since the direction cosines are proportional to M, the quantum number for the component of the angular momentum in the direction of the exterior field (— /field dependent splitting of the rotational level into a pattern of 2/ +1 sublevels which are symmetrically arranged around the zero-field position. 

Zeeman effect The splitting of atomic spectral lines by a magnetic field. This effect was found by the Dutch physicist Pieter Zeeman (1865-1943) in 1896. Some of the patterns of line splitting that be explained both by classical electron theory and the BOHR THEORY of electrons in atoms. The Zeeman splitting that can be explained in these ways is known as the normal Zeeman effect. There exist more complicated Zeeman splitting patterns that cannot be explained either by classical electron theory or the Bohr theory. This more complicated type of Zeeman effect is known as the anomalous Zeeman effect. It was subsequently realized that the anomalous Zeeman effect occurs because of electron spin and that the normal Zeeman effect occurs only for transitions between singlet states. 

At very high magnetic fields a splitting pattern known as the Paschen-Back effect occurs. In this pattern, named for the German spectroscopists Friedrich Paschen and Ernst Back in 1912, the basic pattern returns to that of the normal Zeeman effect, but with each line split up into a set of closely spaced lines. This occurs because the total orbital and spin angular momentum vectors of the atom, denoted L and S respectively, precess independently about the direction of the magnetic field. 

In a magnetic field strong enough to make the split components of adjacent multiplets overlap, we have what is known as the Paschen-Back effect. 2 Once again L and S are uncoupled and the spectral splitting pattern tends toward series of triplets as for the normal Zeeman case with each triplet component itself showing the field-free multiplicity of the transition. 

Although all the examples chosen involve singlet states, for which the theory is especially simple, there is no problem in extending the method to more complex Zeeman patterns, or indeed in including the effect of Paschen-Back uncoupling on the MOV spectrum [166]. The influence of -mixing on MOV patterns has also been studied, and is in principle well understood [167], If the experiment is performed with lasers, the influence of laser power on Faraday rotation arises both by population transfer and by the Autler-Townes splitting (section 9.10) [173]. 

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