Magnetic-Dependent Frequency Shift Arising from Interaction of Two Paramagnetic Spin Types

Abstract

It is shown that in a rigid lattice the previously discarded part of the spin–spin interaction $a_{12}{\mathrm{(S}}_1^{+}{\mathrm{\hspace{0.17em}S}}_2^{-}{\mathrm{\hspace{0.17em}+\hspace{0.17em}S}}_1^{-}{\mathrm{\hspace{0.17em}S}}_2^{+})$ , where S₁ and S₂ are two types of nonequivalent spins, leads to a shift of the resonant frequencies by a term of the form ${\Delta }^2{\mathrm{\nu \hspace{0.17em}/\hspace{0.17em}(\nu }}_{01}{\mathrm{\hspace{0.17em}-\nu }}_{02})$ , where ${\Delta }^2\nu$ is the order of the second moment of the absorption line about either resonant frequency.