7B20.30 - ESR

Code Number:
Demo Title:
Electron Spin Resonance
Area of Study:
Modern Physics
Tel-Atomic ESR apparatus, DPPH sample, Oscilloscope or Laptop with Softscope interface.

This unit is a good demo due to it simple operation.   Assemble the unit as shown.  Set the oscilloscope to X-Y sampling.  Note that the DPPH sample is permanently mounted in the coil unit.  Turn on the main power and adjust the current to approximately 150 ma.  You should see 4 peaks on the oscilloscope.  You can adjust the phase of the coils so that two of the peaks merge with the other two peaks.  The resonant frequency of the sample can be found by adjusting the R.F. Oscillator until resonance is shown on the oscilloscope.  The exact resonant frequency can also be found by very careful adjustment of the R.F. Oscillator.

Additional sample material of the DPPH can be found in the demo room refrigerator.

  • R. Dupree and P. K. Grannell, "A Simple ESR Spectrometer which Uses Sample Heating to Detect Magnetic Resonance", AJP, Vol. 38, #7, July 1970, p. 924.
  • "Simple Electron Spin Resonance Spectrometer", Apparatus Notes, July 1965-December 1972, p. 35.
  • "Electrons Spin Resonance", Alpha Scientific Laboratories.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.