Electron paramagnetic resonance of quasi-one-dimensional crystal [Nd-2(Cl3COO)(6)(H2O)(3)](n) center dot nH(2)O

A quasi-one-dimensional single crystal of [Nd-2(Cl3COO)(6)(H2O)(3)](n). nH( 2)O in which chains are built up of two alternating neodymium-ion dimer fra gments is studied by the EPR technique. It is found that anisotropic intera ctions between neodymium ions in a chain are responsible for the complex sh ape of the EPR spectrum. Two groups of EPR signals are distinguished in the spectrum. Each group corresponds to one of the chain dimers disturbed by t he interaction with neighbors in the chain. The shape of the EPR spectra is interpreted as a superposition of the spectra of chain fragments which hav e different lengths and are formed by the alternating magnetic triplet and nonmagnetic singlet states in the chain. Consideration is given to two case s when two alternating dimer fragments are either equivalent or nonequivale nt to each other. It is shown that the spectral shape is primarily determin ed by the superposition of the spectra of an isolated triplet state (S = 1) , two interacting triplet states, and three interacting triplet states whos e weighting contributions differ for the above two cases. The tensors of th e anisotropic spin-spin interaction are determined, and the contribution fr om the isotropic component of the interaction is estimated. (C) 2001 MAIK " Nauka/Interperiodica".