Electron Spin Resonance Experiment

The basic idea of the electron spin resonance experiment is to flip the spin of an electron by striking the electron with a photon. The electron’s spin will flip only if the photon’s energy hf is equal to the magnetic spin flip energy 2μ B_B.Thus we wish to test the relationship

where f is the frequency of the photon.

In our discussion of the particle nature of light, we pointed out that because a radio wave consists of so many photons of such low energy, it would be difficult to detect individual photons, and thus the wave nature of radio waves should predominate. However the spin of the electron is just the right detector for these low energy photons. An electron spin flip experiment can be viewed as an experimental detection of the individual photons in a radio wave.