The electronic structure of iron phthalocyanine probed by photoelectron and x-ray absorption spectroscopies and density functional theory calculations

Abstract

A joint experimental and theoretical work to explain the electronic and geometrical structure of an in situ prepared film of iron phthalocyanine (FePc) on silicon (100) is presented. FePc molecular films have been characterized by core and valence photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS), and the results have been interpreted and simulated by density functional theory (DFT) calculations. C1s and N1s PE spectra have been analyzed by taking into account all chemically nonequivalent C and N atoms in the molecule. In the Fe2p(32) spectra it has been possible to resolve two components that can be related to the open shell structure of the molecule. By valence PES and N1s XAS data, the geometrical orientation of the FePc molecules in the film could be determined. Our results indicate that for the FePc on Si(100), the molecules within the film are mainly standing on the surface. The experimental N1s XAS spectra are very well reproduced by the theoretical calculations, which are both angle and atomic resolved, giving a detailed description of the electronic and geometric structure of the FePc film. Furthermore, the asymmetry and the intensity angle variation of the first N1s XAS threshold feature could be explained by the presented DFT calculations as due to the chemical nonequivalence of the N atoms and the symmetry character of the lowest unoccupied molecular orbital.

Valence-band electronic structure of iron phthalocyanine: An experimental and theoretical photoelectron spectroscopy study

“…The energy scale of the curves is aligned to the experimental scale, so that the experimental HOMO and the theoretical HOMO are set at the same energy of -6.38 eV. To facilitate the discussion, we have named the main spectroscopical features A to G according to 7 . Peak A is formed by two subpeaks, A 1 , the HOMO, and A 2 .…”

When the Grafting of Double Decker Phthalocyanines on Si(100)-2 × 1 Partly Affects the Molecular Electronic Structure

“…In the case of the D 4h molecule, 33 the XPS energies have the typical splitting of 0.18 eV due to the chemically different nitrogen species (N p and N a ) in the molecule (Fig. 3a).…”

Crystal fields of porphyrins and phthalocyanines from polarization-dependent 2p-to-3d multiplets

“…1 provides quantitative information about the orientation of the deposited films. 1,9,12,13,18,25 The N 1s edge of transition metal phthalocyanines is influenced by the nature of the central metal atom, 42 but we do not focus on these effects here as they do not strongly affect the use of the N 1s edge as a probe of molecular orientation. Well-ordered films were obtained on Si wafers covered with the native oxide, a widely used substrate.…”