The Zeeman effect of the absorption lines of chrome alum crystals cooled to 20deg;K has been photographed for field strengths of from 12,000 to 25,000 gauss. Each of the three strong lines splits into three elliptically polarized components, whose separation of very close to 2ohgr; suggests ``spin only'' orientation in the field. At 50deg;K, but not at 20deg;, the pattern depends upon the orientation of the crystal lattice with respect to the magnetic field. Interaction between closely spaced levels seems to be small and is evidenced only by slight intensity dissymmetries. No shift of the central components from the positions of the fieldhyphen;free lines is observed, and the magnitude of a possible secondhyphen;order Zeeman effect is estimated as less than 10 percent that of the firsthyphen;order effect. The selection rule for the magnetic quantum number, Dgr;m=plusmn;1, 0, seems to be obeyed, making it impossible for the present to decide whether the upper levels belong to the quartet or doublet system. Various possible coupling schemes are considered in the light of the experimental evidence and it is concluded that the actual one existing in chrome alum is either the strong field case in whichLandSdo not interact appreciably andLis almost completely quenched, or the very strong field case in which the coupling of the individuall's is broken down and the individual orbital moments are quenched.
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