Advanced Undergraduate Laboratory

Department of Physics

University of Toronto

ESR: Electron Spin Resonance

Precision measurements of the magnetic moment of the electron have been fundamental in the development and testing of quantum electrodynamics, and in searching for new forces or electron substructure. P. Kusch won the Nobel Prize in 1955 for early measurements of the electron magnetic moment, and ongoing measurements continue to probe for new physics beyond the Standard Model.

Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR), is also very widely used in condensed-matter physics, chemistry, archaeology, geology, environmental science, biology, biochemsitry, pharmacology, medicine, and industry to study both static properties and dynamic processes in almost any system containing radicals (i.e. molecules with unpaired electrons). These applications include everything from detecting tumours to dating ancient material.

This experiment familiarizes students with the generation and transmission of microwave signals, and measures the magnetic moment of the electron in a solid free-radical.


Write-Up in PDF Format or Microsoft Word Format.

(The experiment is currently located in MP226; last write-up revision: February 2010.)

Additional resources:


Photo of Engineering Science student working on experiment.

Shoma Sinha, 3rd year Engineering Sciences Nanotechnology Option student, works on Electron Spin Resonance.

Photo of Engineering Science student ith an excellent oscilloscope resonance trace.

Benjamin Schmidt, 4th year Engineering Sciences Physics Option student, with an excellent oscilloscope resonance trace.

Last updated on 5 February 2019