Author/Authors :
do Rego، نويسنده , , A.M. Botelho and Pellegrino، نويسنده , , O. and Silva، نويسنده , , da and Horowitz، نويسنده , , G. and Kouki، نويسنده , , F. and Gamier، نويسنده , , F. and Vilar، نويسنده , , M. Rei، نويسنده ,
Abstract :
High resolution electron energy loss spectra (HREELS) were recorded for quaterthiophene (4T) films and compared to those of quinquethiophene (5T) and sexithiophene (6T). Excitonic gap was evaluated to be 2.64±0.02 eV. A second threshold appearing in HREELS but not in optical spectra, is assigned to excitation of charge transfer levels with thresholds of 3.6Q±0.02, 3.24±0.02 and 2.97±0.02 eV for 4T, 5T and 6T respectively. Losses between 1.0 and 2.3 eV in 4T and 5T are assigned to S0→Tn transitions. Resonance mechanisms are responsible for induced excitations in the oligothiophene film surfaces.
Keywords :
Polythiophene and derivatives , Polycrystalline surfaces , Semiconducting surfaces , Electron Energy Loss Spectroscopy
