Physical studies of a new conducting charge transfer salt: Tetraselenonaphthalene/tetrafluorotetracyanoquinodimethane (TSeN-TCNQF 4)

Abstract

At room temperature, ESR studies of polycrystalline samples of TSeN/TCNQF 4 show that the salt is weakly paramagnetic. That is, ca 2 out of every 1000 TSeN/TCNQF 4 pairs are paramagnetic. Variable temperature ESR studies reveal that the paramagnetism is activated and that the g-value is strongly temperature dependent. The temperature dependence of the g-value of this material behaves in a manner analogous to that of TTF/TCNQ. Analysis of this temperature dependence indicates that at room temperature there are equal concentrations of TSeN + and TCNQF 4 − and that the two radical species are interacting very strongly. As the temperature is lowered the concentrations of both species decreases but the concentration of the TCNQF 4 − decreases more rapidly. At 83 K, the ratio TSeN+/TCNQF 4 − is ca 5:1. IR transmission studies of the polycrystalline solid at room temperature indicate that the charge transfer from donor to acceptor is at least 90% complete. The conductivity which is activated is 8 × 10 −7 S/cm at room temperature.