Photoemission of ferrocene, decamethylferrocene, and decamethylferrocene-bis(7,7,8,8-tetracyano-p-quinodimethane)

We present the first vacuum ultraviolet photoemission measurements of condensed ferrocene, decamethylferrocene, and the highly conductive charge transfer complex decamethylferrocene-7,7,8,8-tetracyano-p-quinodimethane, at photon energies from 7.7 to 21.2 eV. We compare the electronic spectra of these compounds and discuss substituent effects. The first ionization potentials are 6.1, 5.1, and 5.3 eV, respectively. The charge transfer complex is a semiconductor with its highest occupied states 0.8 eV below Er. The electron scattering lengths in ferrocene and decamethylferrocene are ~ 60 A. for electrons 0.5 eV above the vacuum level and decrease to ~ 2.5 A(o). as the energy is increased to 16 eV. From this result we estimate the electron affinity of solid ferrocene and decamethylferrocene. to be about 1 eV.