Electronic structure and orientation of anthracene on Ag(111)

Core level photoemission studies of the interaction of pentacene with the Si(111) (7×7) surface

“…This can be deduced from the polarisation data in that the related molecular orbitals are more pronounced under p-polarised illumination. This is the opposite to that observed in the valence band spectra for the horizontally lying pentacene molecule on the silver terminated Si(1 1 1) surface [9] and is consistent with the polarisation dependence reported by Yannoulis et al [10] for the interaction of thin anthracene films on the Ag(1 1 1) surface. Weidkamp et al [3] have also reported that molecular layers adsorbed above the chemically bound first layer are more likely to adopt a more electronically favourable crystal structure which would involve the molecules adopting a more upright orientation on the passivated surface.…”

The role of the van der Waals interactions in the adsorption of anthracene and pentacene on the Ag(111) surface

“…4(c)) shows a pronounced peak at 2.33 eV below the Fermi level, which is in good agreement with the experimental observation of a π-character band at the top of the valence band located at 2.5 eV below the Fermi edge 5 . Both PBE and HSE functionals, however, fail to describe the position of the LUMO; we found that the LUMO is located right above the Fermi level (0.37 eV from PBE and 0.64 eV from HSE calculation) whereas inverse photoemission measurements 5 have shown that the LUMO is located between 2 and 3 eV above the Fermi level. This underestimation is mainly due to the inability of KohnSham energy levels to describe excited states.…”

“…Figs. 4(b) and (c) also show that both PBE and HSE calculations predicted that the LUMO remains unoccupied on the Ag(111) surface, indicating that there is no charge transfer between the substrate and the molecule and that anthracene is physisorbed on Ag(111), which is consistent with previous experimental studies 5,7 .…”

“…Experimental studies have reported that both anthracene and pentacene monolayers weakly adsorb on Ag(111), as characteristic of physisorption or weak chemisorption [5][6][7][8][9][10] , which suggests that van der Waals interactions (vdW) play an important role in the binding of these systems.…”

Analysis of the near-edge X-ray-absorption fine-structure of anthracene: A combined theoretical and experimental study

“…Surprisingly, no high-resolution NEX-AFS data (neither for gas-phase nor for solids) have been published so far for this acene. Only low-resolution NEX-AFS spectra were reported for thin films adsorbed on Ag(111) and TiO 2 (110) which in both cases reveal no distinct fine structure [32,33]. To provide high resolution reference data without intensity variations of individual resonances due to orientational effects and to exclude electronic distortions owing to chemical interaction with the supporting substrate the present NEXAFS data were acquired for powder samples and are compared with calculated spectra.…”