ArcAdiA

Experimental and Theoretical Investigation of the Pyrrole/Al(100)Interface

Mon, 30 Nov 2009 23:00:00 GMT

Experimental and Theoretical Investigation of the Pyrrole/Al(100)Interface Ruocco, Alessandro; Chiodo, Letizia; Sforzini, Massimo; Palummo, Maurizia; Monachesi, Patrizia; Stefani, Giovanni 2009-12 The journal of physical Chemistry A 113 15193-15197 The electronic properties of the pyrrole/Al(100) interface have beeninvestigated from both a theoretical and experimental point of view.Electron energy loss spectroscopy (EELS) in specular reflectiongeometry does not reveal modification of the electronic structure ofthe molecule when adsorbed on the Al surface. EELS results and the lowdesorption temperature of pyrrole indicate a weak molecule/metalinteraction. Ab initio calculations in the framework of thesingle-particle density functional theory within the local densityapproximation was used to investigate the adsorption energy andgeometry. The low adsorption energy, -0.51 eV per molecule, and thehigh N-Al distance, 1.98 angstrom, confirm the weak interaction ofpyrrole adsorbed on the Al Surface.

M3M45M45 Auger lineshape measured from the Cu(111) surface: Multiplet term selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy

Sat, 31 Jan 2009 23:00:00 GMT

M3M45M45 Auger lineshape measured from the Cu(111) surface: Multiplet term selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy Gotter, R.; Da Pieve, F.; Offi, Francesco; Ruocco, Alessandro; Verdini, A.; Yao, H.; Bartynski, R.; Stefani, Giovanni 2009-02 Physical Review B 79 075108 The capability of the recently observed dichroic effect inangle-resolved Auger-photoelectron coincidence spectroscopy (DEAR-APECS) to disentangle individual multiplet terms has been exploited to study the lineshape of the M3M45M45 Auger spectrum measured in coincidence with the 3p(3/2) photoelectrons from theCu(111) surface. The relevant multiplet structure of the two hole final state is determined with an unprecedented sensitivity, including are liable experimental estimation of the energy of the D-1 multipletterm. Spectroscopic data for the 3p photoemission feature are also given and energy conservation applied to the photoelectron-Auger-electron pair has been successfully used in orderto quantitatively explain energy shifts in coincidence spectra. Multiple-scattering calculations prove that the DEAR-APECS effect is not destroyed by diffraction effects and a simple model which combines atomic angular distributions and electron-diffraction modulations is provided in order to obtain a detailed understanding of the multiplet energy and intensity distributions in Auger spectra.

Electronic states of CuPc chains on the Au(110) surface

Sat, 31 Oct 2009 23:00:00 GMT

Electronic states of CuPc chains on the Au(110) surface Evangelista, Ferdinand; Ruocco, Alessandro; Gotter, Roberto; Cossaro, A.; Floreano, L.; Morgante, A.; Crispoldi, F.; Betti, M. G.; Mariani, C. 2009-11 Jurnal of chemical physics 131 174710 The electronic properties of Cu-phthalocyanine (CuPc) molecules flatlying along the channels of the Au(110) reconstructed surface have beeninvestigated by means of ultraviolet and x-ray photoelectronspectroscopy. The ordered chains give rise to a highly orderedsingle-layer structure with a (5x3) symmetry. Although from thecore-level analysis not any significant charge transfer between themolecules and the underlying Au surface is observed, the valence bandphotoemission data bring to light CuPc-induced features localized atthe interface. In particular, energy versus momentum dispersion of aninterface state reveals a bandwidth of about 90 meV along the enlargedAu channels, where the CuPc chains are formed, with a defined fivefoldsymmetry well fitting the CuPc intermolecular distance.