A single layer (SL) of pentacene molecules deposited on the Cu(119) surface and on an organic self- assembled monolayer (SAM) has been investigated by near-edge x-ray absorption ﬁne structure (NEXAFS) at the C K edge, and by photoemission at the C 1s core level. The lowest unoccupied molecular orbitals (LU- MOs) of the pentacene SL on the SAM are basically unaffected with respect to that of pentacene in the gas phase, indicating a weak interaction of pentacene with the SAM, while a strong redistribution of the LUMO- related ﬁnal states is observed when the molecules are deposited on the Cu(119) substrate, sign of an electronic mixing between molecular and metal electronic states, in agreement with recent theoretical predictions. The strong dichroic response of the NEXAFS signal indicates upstanding pentacene molecules oriented 16° off normal for the organic-organic heterostructure. The rehybridization of pentacene orbitals with Cu states at the pentacene/Cu interface hinders an accurate determination of the molecule orientation, which is, however, compatible with molecules lying ﬂat on the Cu(119) terraces.
|Titolo:||Interaction strenght and molecular orientation of a single layer of pentacene in organic-metal interface and organic-organic heterostructure|
|Parole Chiave:||adsorption ; copper ; EXAFS ; metal-insulator boundaries ; monolayers ; organic compounds ; photoemission ; self-assembly ; XANES|
|Data di pubblicazione:||14-mar-2008|
|Digital Object Identifier (DOI):||10.1103/PhysRevB.77.115321|
|Appare nelle tipologie:||01 - Articolo su periodico|