The magnetic moment of Se2

Abstract

Atoms of the oxygen group form diatomic molecules with a multiplet ground state. Of these, O₂ and S₂ conform to Hund’s (b) coupling and have an appreciable magnetic moment, whereas Te₂ is better described as having case (c) coupling with a very small effective magnetic moment. Although the Se₂ molecule is intermediate between these two cases, it is closer to case (c) than to case (b). A method of calculating the magnetic moment and Zeeman effect of a molecule of this series with Hund’s case (c) coupling is described and applied to Se₂. The calculations result in a value of 5.97×10⁻² μ_B for the mean effective moment of the Se₂ molecule at 1000 K in a field of 14 kG. This value was found to be consistent with the results obtained experimentally by the use of a molecular beam deflection technique similar to that of Stern and Gerlach.