The technique of electron paramagnetic resonance has been applied to study the magnetic properties of nickel acetate and nickel potassium tutton salt single crystals, using Mn2+ ion as probe. From the values of spin Hamiltonian parameters and linewidths at room, liquid nitrogen and liquid helium temperatures it is concluded that these crystals do not become magnetically ordered as the temperature is lowered to 3.2K, and thus the transition temperature, below which the crystal would order either ferromagnetically, or antiferromagnetically, for these crystals, should be below 3.2K.

A method, different from the classical ones, for studying internal motions - in particular reorientational and tunneling modulation of rotations - via NMR is described. Instead of looking for matching or resonance maxima in NMR T1−1 vs. T - curves [ where o (↗)≅ωo,with ρ the correlation rate and ωo: the Larmor frequency] we look for such maxima in NMR T1−1 vs. ωo - curves [where ω =↗o, with ω: the (tunneling)frequency]. These method, Nuclear Magnetic Resonance Relaxation Resonance (NMRRR), has marked advantages, which are discussed. A field cycling technique is presented. Typical results, for solid silane, are given.

The effect of atomic and molecular motions on the NMR free-induction decay (FID) and lineshape is investigated theoretically in the intermediate temperature range in which the NMR line is only partially narrowed. It is shown that the FID may be decomposed into the weighted sum of a rigid-lattice (background) contribution and an exponentially decaying part containing all the information on the diffusive or reorientational motions in the crystal in terms of the spin-spin relaxation time T2.

We discuss a recently developed technique for studying the diffusion of spins with a small gyromagnetic ratio and apply it to investigate the nature of Ag+diffusion in AgF. We also investigate the potential application of this technique to the observation of diffusing impurities. Experimental studies on Cu:3% Al and (P2O5).8(Li2O).2 glass are described.

One of the parameters of interest in studies on dilute alloys is the ratio of the effective host-host to impurity-host interaction. A method is presented which allows the evaluation of the effective impurity-host force-constant ratio, A′/A, for substitutional, isolated, impurity atoms in a cubic lattice by combining recoilless-fraction data (Mössbauer effect) of the impurity atoms with x-ray– or neutron-diffraction data of the host lattice. With this method, values of A′/A are obtained for dilute 57Fe impurities in various hosts.

The effect of the isotopic mass on the redistribution of electron charge and spin density around a light impurity such as hydrogen in metals has been studied. Considered in this review are: (a) the magnetic hyperfine coupling to the hydrogen nucleus and the effect of isotopic mass, (b) the isotope effect in hydrogen impurity resistivity, (c) the reverse isotope effect in superconducting PdH(D) and (d) the thermally induced detrapping of hydrogen from the vicinity of solute sites in metallic hosts.