The potential energy of an atomic magnetic dipol in a magnetic field is quantized, and the energy splitting increases linearly with increasing field. For magnetic fields in the sub-tesla range, the energy splittings are typically in the energy range microwaves with frequencies in the GHz range. In this experiment, the paramagnetic material CuSO4 is investigated. The sample put inside a microwave resonator, which is located in the field center of an electromagnet. While the magnetic is slowly varied, the transmitted microwave intensity is continuously measured in order to observe the resonance between the field-induced energy splitting and the microwave energy. The resonance field and the lineshape of the resonance yield information about the local structure of the dipols and their interaction.

• tutorial of the experiment
• Ref. 7
• Ref. 8
• Ref. 9