General Magnetic Transition Dipole Moments for Electron Paramagnetic   Resonance
  We present general expressions for the magnetic transition rates in beam Electron Paramagnetic Resonance (EPR) experiments of anisotropic spin systems in the solid state. The expressions apply to general spin centers and arbitrary excitation geometry (Voigt, Faraday, and intermediate). They work for linear and circular polarized as well as unpolarized excitation, and for crystals and powders. The expressions are based on the concept of the (complex) magnetic transition dipole moment vector. Using the new theory, we determine the parities of ground and excited spin states of high-spin (S = 5/2) Fe(III) in hemin from the polarization dependence of experimental ground state EPR line intensities. 
Joscha Nehrkorn, Alexander Schnegg, Karsten Holldack, Stefan Stoll
cond-mat.mes-hall