Multiplet structure in the 35,37Cl ligand electron nuclear double resonance spectra of single crystals of Cu(II)-doped histidine hydrochloride monohydrate

Abstract

Multiplet structure was observed at 4.2 K in the 35,37Cl ligand electron nuclear double resonance (ENDOR) spectra of single crystals of Cu(II)–doped histidine hydrochloride monohydrate. By using second-order perturbation theory we show clearly that the observed multiplet structure arises from the 63Cu and 35,37Cl indirect nuclear spin–spin interaction. Our theoretical analysis in general because it encompasses the anisotropies of both the g and hyperfine tensors, and also allows for the quantization of the nuclear spins along the effective field at each nucleus.