Electron paramagnetic resonance (EPR)

Introduction to technique:
  • The theory of EPR can be found in any number of textbooks, including ones by Drago [R.S. Drago, Physical Methods for Chemists, HBJ Publishing, Ft. Worth, TX, 1992], Abragam [A. Abragam, Electron Paramagnetic Resonance of Transition Metal Ions, Oxford, Clarendon Publishing, New York, 1970], and more recently, Solomon and Lever [A. Bencini, D. Gatteschi, in: E.I. Solomon, A.B.P. Lever (Eds.), Inorganic Electronic Structure and Spectroscopy, vol. 1, Wiley, New York, 1999, p. 93].
  • EPR spectroscopy examines the transitions between electron spin states separated by the presence of an external magnetic field. These states are separated by an energy dependent on the g value of the observed species (for the theoretical ‘free’ electron, g=2.0023) and the magnetic field applied, as shown in Fig.1 

Figure. 1.         The spin state transitions observed in the EPR are shown here for a system with both electron spin S=1/2 and nuclear spin I=1/2.

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