Assignment for Zero-Field Splitting the Zeeman Term

Assignment for Zero-Field Splitting the Zeeman Term 

The spin Hamiltonian Eq. (1) has well-known solutions when the microwave frequency is less than the zero-field splitting D (at X-band, v 9.4 GHz or vie 0.3 cm ). The six energy levels for S = 5/2 arrange in three Kramers doublets at zero field and, for D large compared with h v, diverge linearly with magnetic field until the fields are larger than usually used for X-band spectroscopy  

When the energies are small relative to kT, series expansions of the exponentials give the approximation Eq. (3) for the temperature dependence of relative intensi- 

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