Polarization energies of tetrathiafulvalene derivatives

Abstract

Ultraviolet photoelectron spectroscopic studies were carried out on dimethyl-, tetramethyl- and dibenzo-derivatives of tetrathiafulvalene in the gaseous and solid state. As the difference between the threshold ionization potentials in both states, we obtained the polarization energies of those compounds in the solid state. Dibenzotetrathiafulvalene (DBTTF) showed the differential relaxation shifts due to the different electronic bands. Polarization energies of the two methyl-derivatives are very small, 0.9 and 1.1 eV. While that of DBTTF is the largest, 2.3 eV, among the donor-like compounds measured, due to the large molecular polarizability. Comparing these values with the polarization energies of related compounds, it is suggested that the DBTTF form very stable charge-transfer complexes with some appropriate acceptor molecules