Electron-Phonon Coupling in Crystalline Pentacene Films

The electron-phonon (e-p) interaction in pentacene (Pn) films grown on Bi(001) was investigated using photoemission spectroscopy. The spectra reveal thermal broadening from which we determine an e-p mass enhancement factor of λ=0.36±0.05 and an effective Einstein energy of ωE=11±4 meV. From ωE it is inferred that dominant contributions to the e-p effects observed in angle-resolved photoemission spectroscopy come from intermolecular vibrations. Based on the experimental data for λ we extract an effective Peierls coupling value of geff=0.55. The e-p coupling narrows the highest occupied molecular orbital bandwidth by 15±8% between 75 and 300 K.