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A: Atomphysik
A 7: Atome in äußeren Feldern
A 7.2: Talk
Tuesday, April 4, 2000, 14:15–14:30, HS II
The field dependence of the magnetic moment in doublet states — •M. Brieger — DLR, Institut für Technische Physik, Pfaffenwaldring 30-40, D-70569 Stuttgart
Like for a classical magnetic dipole, the energy of an atomic magnetic moment also shows orientational dependence in an external magnetic field in terms of the quantum mechanically fixed MJ values. Analogous to the classical case, this energy varies linearly for weak field strengths with a slope that is proportional to the gJ factor in this Zeeman regime. As this factor is a measure of the intrinsic magnetic moment of the atomic fine-structure eigenstate, the analogy with the behavior of a classical dipole has led to the conclusion that weak fields affect the intrinsic magnetic moment only negligibly. Relying on this to be true, quite some endeavors have been undertaken in the past by measuring gJ values as precisely as possible in order to obtain hints to possible relativistic and/or binding corrections from deviations between measured and theoretical results. In this contribution, however, we will show that the gJ value only holds true for B = 0. While the magnetic moment varies dramatically even in weak fields, the quasi-linear weak-field behavior of the energy eigenvalues is brought about by an almost perfect compensation of the counteracting quadratic field dependences of the energy of the magnetic moment and of the spin-orbit interaction.