Charge and spin locations in linear stacks of TCNQ

Abstract

Charge and spin locations in stacks of TCNQ molecular ions are assessed. The fine-structure parameters of localised triplet excitons extending over three and four molecules in the stack are calculated relative to the fine-structure splitting of the TCNQ^2–₂ dimer: the absence of resolved fine-structure is shown to be insufficient evidence for the absence of localised exciton traps. Both the charge and spin locations are assumed to be especially sensitive to the relative values of the intermolecular charge interaction and electron resonance. Spin magnetic susceptibilities observed in pyridinium TCNQ salts, which may derive from spin traps, spin excitons and free-electrons separately or in combination, are differentiated into these three components.