In-situ metalation of porphyrin molecules in ultrahigh vacuum (UHV) is of great interest for the characterization of pure species in a controlled environment. Here, we report the characterization of the electronic states and the moleculesʼ geometrical adaptation during the formation of pure 2H-5,10,15,20-tetraphenylporphyrin (2H-TPP) and Fe- tetraphenylporphyrin (Fe-TPP) layers on Ag(111) single crystal. Core level absorption spectra indicate the flat conformation of the monolayer suggesting an adatom hopping instead of a surface mediated dopant diffusion for the metalation process. Photoemission points out that the interaction between Fe d z -states and Ag bands increases the monolayer metallic character already induced by the charge transfer from the substrate.

The electronic structure and the geometric arrangement of picene molecules adsorbed on Ag(111) were studied by means of photoemission and near-edge X-ray absorption fine-structure spectroscopies (NEXAFS). While the valence band of a picene monolayer shows a clear metallic state that evolves with alkali metal doping, in the case of a picene multilayer there is no evidence of metallic states evolving with doping. Our data suggest that the bulk ultrahigh-vacuum films of K x picene are in an insulating phase, and we attribute this behavior to a strong electron–electron Coulomb interaction that is instead screened in the monolayer. The NEXAFS profiles of different picene layers show a coverage-dependent orientation, from flat molecules (monolayer) to an orientation of ∼40° of the molecular long axis with respect to the substrate surface (multilayer). The observed molecular orientations are in disagreement with the expected crystal structure of the bulk material and may explain the presence of insulating states in strongly correlated doped picene multilayers.

Growth conditions, structural, and optical properties of MgO nanostructure have been investigated. Surface composition and shift in binding energy of Mg at 50.8 eV due to oxidation were examined by core-level spectroscopy. The SEM showed that the film is dense, and grain growth and crystallinity are enhanced by post-deposition annealing. Grain distribution was appraised within the confinement of 24.51 μm 2 from the selected scan areas. X-ray diffraction studies indicated prominent peaks, which are attributed to (111), (200), and (220) reflections from fairly crystallized and randomly oriented MgO thin film. Plane (111) is found to be the preferred orientation of the film. The film transmitted well across the visible spectrum and the estimated energy band gap is 5.41 eV. Absence of catalyst in the electrolyte solution aided the purity of the sample.