X-ray diffuse scattering and magnetic resonance: a study of structural phase transitions in perylene radical cation salts

The quasi-one-dimensional organic conductors di-perylene hexafluorophosphat e and -antimonate undergo three and two structural phase transitions below room temperature, respectively. The unequivocal structural proof of the Pei erls transition at T-P in both compounds is provided by X-ray diffuse scatt ering experiments. The characterization of the structural phase transitions above T-P is done using the analysis of X-ray patterns together with previ ously known ESR results. The combined techniques offer new insight into the relative displacements and rotations of the perylene stacks. The relations hip between the Peierls transition and the precursor transitions is discuss ed. (C) 2000 Elsevier Science S.A. All rights reserved.