ABSTRACT
We have studied the production of doubly charged molecular ions by a single photon for the aromatic molecules triphenylene (C18H12) and corannulene (C20H10) using monochromatized synchrotron radiation from 18 eV to 270 eV. We compare our results with previously published data for partially deuterated benzene (C6H3D3), pyrene (C16H10), and coronene (C24H12). The question that we address in this paper is how the different but similar molecular structures of coronene, corannulene, and triphenylene affect the photon-energy dependence of the ratio of doubly to singly charged parent ions. A theoretical analysis of the main features in terms of independent molecular subsystems will be discussed.
ABSTRACT
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 lambda=0.36+/-0.05 and an effective Einstein energy of omega{E}=11+/-4 meV. From omega{E} 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 lambda we extract an effective Peierls coupling value of g{eff}=0.55. The e-p coupling narrows the highest occupied molecular orbital bandwidth by 15+/-8% between 75 and 300 K.
