A photoemission study using synchrotron radiation of in-situ synthesized organic conductors (DMe-DCNQI)2Cu and (MeBr-DCNQI)2Cu is reported, where DMe-DCNQI and MeBr-DCNQI are dimethyl-N,N′-dicyanoquinonediimine and methyl, bromine-N,N′-dicyanoquinonediimine, respectively. The photon energy dependence of the valence band spectra is used to characterize the origin of the observed features. In both salts, the Cu 3d derived states are situated at 3.5-4 eV binding energy, while the C and N 2pσ states appear around 7.5 eV. The Br 4p states are found around 5 eV in (MeBr-DCNQI)2Cu. The states near the Fermi level have substantial C and N 2pπ character consistent with extended Hückel molecular orbital calculations. The absence of a resonance at the Cu 3p threshold suggests a small contribution of Cu2+ configuration in DCNQI-Cu salts.
- 0511 photoelectron spectroscopy
- chemical synthesis
- electronic band structure
- organic crystals
- synchrotron radiation