Paramagnetic Resonance Absorption of Copper Ions in Porous Crystals

Abstract

The EPR absorption of Cu II ions in porous crystals was studied. The effect of Cu concentration, adsorbed phases, and structure of the crystal on the EPR of Cu+ + ions is discussed in detail. For small Cu II concentrations, the EPR spectrum obtained is in accord with the theory of Sands for polycrystalline Cu‐containing solids. Further, by choosing the appropriate crystal type and physical state it was possible to resolve the hyperfine structure due to the Cunuclear moment, both in the g∥ and g⊥ bands, and thus obtain values for A and B. Our data fit the following Hamiltonian: H =β 0 [g ‖ H z S z +g ⊥ (H x S x +H y S y )]+A S z I z +B(S x I x +S y I y ). Using the analysis of Maki and McGarvey, we obtained values of α, β1, β and ``K'' which characterized the type of bonding of Cu II ions in the crystal lattice. From the variation of A, g, β, and ``K 0'' parameters, the mechanism and process of adsorption of water on these crystals were ascertained. Some results obtained on Cu II containing hydrated crystals are compared to some Cu II ions in different solutions.