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We have measured the transformation of pseudomorphic Ni films on Pd(100) into their bulk fcc phase as a function of the film thickness. We made use of x-ray diffraction and x-ray induced photoemission to study the evolution of the Ni film and its interface with the substrate. The growth of a pseudomorphic film with tetragonally strained face centered symmetry (fct) has been observed by out-of-plane x-ray diffraction up to a maximum thickness of 10 Ni layers (two of them intermixed with the substrate), where a new fcc bulk-like phase is formed. After the formation of the bulk-like Ni domains, we observed the pseudomorphic fct domains to disappear preserving the number of layers and their spacing. The phase transition thus proceeds via lateral growth of the bulk-like phase within the pseudomorphic one, i.e. the bulk-like fcc domains penetrate down to the substrate when formed. This large depth of the walls separating the domains of different phases is also indicated by the strong increase of the intermixing at the substrate-film interface, which starts at the onset of the transition and continues at even larger thickness. The bulk-like fcc phase is also slightly strained; its relaxation towards the orthomorphic lattice structure proceeds slowly with the film thickness, being not yet completed at the maximum thickness presently studied of 30 Angstrom (i.e. about 17 layers)., 8 pages, 7 figures

Organic molecule-metal interfaces are relevant both for theirtechnological applications and for the knowledge of the earlystage of the adsorption. In this context the interface propertiesplay an important role in determining the adsorbate orderingand its electronic properties. In this work we present theelectronic properties and the growth morphology of the CuPcmolecule grown on Al(100) and Au(110) surfaces. These twometals have completely di.erent properties that influence thenature of the interface. Al is a prototype of a free electronmetal and the CuPc/Al(100) interface is characterized by asignificant charge transfer as observed by the disappearanceof the HOMO-LUMO transition in the EELS spectra at lowcoverage [1]. Strong evidence of the interaction between themolecule and Al substrate also come from XPS [2] where weobserve the disappearance of the shake-up satellites in the C1s spectra and the complete reduction of copper for the lowestcoverages. On the contrary Au is characterized by a stronglocalization of d electrons and a low density of delocalized selectrons. For the CuPc/Au(110) interface we observe less important modification of the electronic structure of the moleculewith respect to the CuPc/Al(100) interface. Nonetheless theinteraction between the molecule and the Au substrate is notnegligible. In fact HR-UPS study has shown the presence ofinterface states [3]. From a morphological point of view weobserve that CuPc grown on Au(110) gives rise to di.erentsymmetry of the interface as a function of the CuPc thickness:the 1x2 clean Au reconstruction evolves in a 5x5 and in a 5x3reconstruction as observed by LEED. The Au(110) surface ismade by long channels of missing atoms that act as a guidefor the adsorption of the molecules. Along the direction of thechannels we observe a periodicity that match the dimension ofthe molecule, while along the other direction the x2 reconstructionof the Au atoms disappears after a deposition of a fractionof monolayer and it evolves in the x5 and the x3 reconstruction.As pointed out by GIXD [4], these reconstructions along the [001] direction is due to a rearrangement of the uppermostgold atoms. The CuPc/Al(100) interface does not show anylong range order. For the lowest coverage the strong interactionsuggests a flat lying deposition while for thicker film, XASdata indicate the growth of CuPc layer with the plane of themolecule perpendicular to the surface.

The electronic properties of thin metallic films deviate from the corresponding bulk ones when the film thickness is comparable with the wavelength of the electrons at the Fermi level due to quantum size effects (QSE). QSE are expected to affect the film morphology and structure leading to the low temperature (LT) ``electronic growth'' of metals on semiconductors. In particular, layer-by-layer growth of Pb(111) films has been reported for deposition on Ge(001) below 130 K. An extremely flat morphology is preserved throughout deposition from four up to a dozen of monolayers. These flat films are shown to be metastable and to reorganize into large clusters uncovering the first Pb layer, pseudomorphic to the substrate, already at room temperature. Indications of QSE induced structural variations of the growing films have been reported for Pb growth on Ge(001), where the apparent height of the Pb(111) monatomic step was shown to change in an oscillatory fashion by He atom scattering (HAS) during layer-by-layer growth. The extent of the structural QSE has been obtained by a comparison of the HAS data with X-ray diffraction (XRD) and reflectivity experiments. Whereas step height variations as large as 20 % have been measured by HAS reflectivity, the displacement of the atomic planes from their bulk position, as measured by XRD, has been found to mainly affect the topmost Pb layer, but with a lower extent, i.e. the QSE observed by HAS are mainly due to a perpendicular displacement of the topmost layer charge density. The effect of the variable surface relaxation on the surface vibration has been studied by inelastic HAS to measure the acoustic dispersion of the low energy phonons., Comment: 28 pages (laTex,elsart) and 13 figures (eps); updated references

The bonding geometry of the C-N molecule in the saturated c(2 x 2) layer on the Pd(110) surface has been determined by combining polarization-dependent near edge x-ray absorption fine structure and full-solid-angle x-ray photoelectron diffraction (PED). The N K-edge spectra display a strong dependence on the polar and azimuthal orientation of the light polarization with respect to the sample surface. A strong forward scattering peak along the [001] direction is present in the full-solid-angle photoelectron diffraction data of the C1s core level. Both the position of the C1s PED forward scattering peak and the angular dependence of the N K-shell absorption spectra provide direct evidence that the CN molecules is oriented with the molecular axis along the [001] surface direction, at variance with earlier conclusions based on angle-resolved valence level photoemission data. The forward scattering peak in the C1s PED data further indicates that the N atoms lie above the C atoms, with the C-N molecular axis tilted by 25degrees +/- 4degrees with respect to the surface plane. The close analogy of this geometry with the results of previous structure determinations of CN adsorbed on Ni and Rh (110) surfaces is discussed.

Équipe 102 : Surfaces et Spectroscopies; International audience; We provide insight into surface-catalyzed dehalogenative polymerization, analyzing the organometallic intermediate and its evolution into planar polymeric structures. A combined study using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and first-principles calculations unveils the structural conformation of substrate-bound phenylene intermediates generated from 1,4-dibromobenzene precursors on Cu(110), showing the stabilizing role of the halogen. The appearance of covalently bonded conjugated structures is followed in real time by fast-XPS measurements (with an acquisition time of 2 s per spectrum and heating rate of 2 K/s), showing that the detaching of phenylene units from the copper substrate and subsequent polymerization occur upon annealing above 460 +/- 10 K.

We find that for adsorbed terephthalic acid (TPA) molecules surface Sn alloying deactivates the Cu(001) surface by decoupling the adsorbed molecules from the substrate. This effect is investigated for the case of the 0.5 ML phase of the Sn/Cu(001) surface alloy by applying fast X-ray photoemission spectroscopy, scanning tunneling microscopy, near-edge Xray absorption fine structure spectroscopy, and density functional theory calculations. The experimental results conclusively show that the deprotonation reaction of the carboxyl groups occurring in the clean Cu(001) is fully inhibited on this Sn/Cu(001) surface alloy, which allows the molecules to form two-dimensional arrays stabilized by [OH···O] hydrogen bonds. The formed arrays exhibit a crystal structure that is practically indistinguishable from that theoretically obtained for unsupported TPA sheets, suggesting an extremely weak molecule/substrate interaction. This is supported by DFT calculations of the adsorption energy landscape of the TPA sheets formed on the Sn/Cu(001) template: the lateral variation of the adsorption energy (corrugation) is estimated to be less than 0.2 eV, with an adsorption energy per molecule in the range 1.6−1.8 eV and a contribution of each double [OH···O] bond of 1 eV. Finally, the performed thermal desorption experiments show that the TPA sheets remain stable on the surface alloy until their desorption. From these experiments, a value of 1.5 eV was determined for the desorption energy barrier, which is consistent with the important contribution of the [OH···O] bonds to the stability of the sheets as theoretically predicted. The results reported in this study suggest that a gradual activation of the interaction between the TPA molecules and the Cu(001) surface will also be obtained for decreasing Sn coverage. Fil: Carrera, Alvaro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Cristina, Lucila Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Bengió, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Cossaro, A. . Italian National Research Council. Istituto Officina dei Materiali; Italia Fil: Verdini, A. . Italian National Research Council. Istituto Officina dei Materiali; Italia Fil: Floreano, L.. Italian National Research Council. Istituto Officina dei Materiali; Italia Fil: Fuhr, Javier Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Gayone, Julio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Ascolani, Hugo del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina

Surface-assisted cyclodehydrogenation and dehydrogenative polymerization of polycyclic (hetero)aromatic hydrocarbons (PAH) are among the most important strategies for bottom-up assembly of new nanostructures from their molecular building blocks. Although diverse compounds have been formed in recent years using this methodology, a limited knowledge on the molecular machinery operating at the nanoscale has prevented a rational control of the reaction outcome. We show that the strength of the PAH–substrate interaction rules the competitive reaction pathways (cyclodehydrogenation versus dehydrogenative polymerization). By controlling the diffusion of N-heteroaromatic precursors, the on-surface dehydrogenation can lead to monomolecular triazafullerenes and diazahexabenzocoronenes (N-doped nanographene), to N-doped oligomeric or polymeric networks, or to carbonaceous monolayers. Governing the on-surface dehydrogenation process is a step forward toward the tailored fabrication of molecular 2D nanoarchitectures distinct from graphene and exhibiting new properties of fundamental and technological interest., We acknowledge financial support by Spanish research projects Nos. MAT2011-26534, CSD2007-41, CTQ2010-18813, and S2009/MAT-1756/CAM, the Czech Science Foundation project No. P207/10/2207, and the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic (RVO: 61388963).

he structure of Fe films grown on the (001) surface of a Cu3Au single crystal at room temperature has been investigated by means of grazing incidence x-ray diffraction (GIXRD) and photo/Auger-electron diffraction (ED) as a function of thickness in the (3-36)-Angstrom range. The combination of GIXRD and ED allows one to obtain quantitative information on the in-plane spacing a from the former technique, and the ratio between the vertical spacing c and a, from the latter one. At low coverage the film grows pseudomorphic to the face-centered-cubic substrate. The experimental results obtained on a film of 8 Angstrom thickness clearly indicate the overcoming of the limit for pseudomorphic growth. Above this limit the film is characterized by the coexistence of the pseudomorphic phase with another tetragonally strained phase gamma, which falls on the epitaxial line of ferromagnetic face-centered cubic Fe. Finally, the development of a body-centered phase alpha, whose unit cell is rotated by 45degrees with respect to the substrate one, has been clearly observed at similar to17 Angstrom. alpha is the dominating phase for film thickness above similar to25 Angstrom and its lattice constant evolves towards the orthomorphic phase in strict quantitative agreement with epitaxial curves calculated for body-centered tetragonal iron phases.

The adsorption and self-assembling properties of terephthalic acid (TPA) molecules deposited on Cu(001) at room temperature have been systematically studied using both experimental and theoretical tools. The system forms two phases at room temperature, the metastable β-phase and the stable 3×3 one. In the case of the β phase, the low-energy electron diffraction and scanning-tunneling microscopy (STM) results indicate that the β phase has a (9 √ 2×2 √ 2)R45◦ unit cell with exactly the same molecular coverage as the 3×3 phase. In addition, the high-resolution X-ray photoelectron spectroscopy O1s spectra indicate that the irreversible β → 3 × 3 transition involves the following two processes: i) deprotonation of the complete carboxyl groups remaining in the metastable phase and ii) re-arrangement of the molecules into the 3×3 configuration. On the other hand, we explored possible molecular configurations for the β phase with different degree of deprotonation (including structures with Cu adatoms) by means of density functional theory calculations. Our theoretical results indicate the formation of strong bonds between the O atoms in carboxylates and the Cu atoms of the surface, which causes a bending of the molecules and a buckling of the first Cu layer. In the 3 × 3 phases, we show that the bending produces observable effects in the molecular STM images. We also observed that the strong interaction between the carboxylates and the Cu atoms at the step edges drives the reorientation of the surface steps along the < 100 > crystallographic directions. Fil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carrera, Alvaro Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Murillo Quiros, Natalia Maria. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cristina, Lucila Josefina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cossaro, Albano. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; Italia Fil: Verdini, Alberto. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; Italia Fil: Floreano, Luca. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; Italia Fil: Gayone, Julio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ascolani, Hugo del Lujan. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The control of the electronic properties of the interfaces between small organic molecules and the substrate is key for the development of efficient and reliable organic-based devices. A promising and widely covered route is to interpose a Self-Assembled Monolayer (SAM) to bridge the molecular film and the electrode. The morphology and the electronic level alignment of the triple substrate-SAM-organic layered system can be tuned by properly selecting the SAM composition. We have recently proposed a novel approach to the problem where, under ultra-high vacuum conditions, a molecular film is anchored to the SAM by exploiting the recognition between molecules functionalized, respectively, with -NH(2) and -COOH end-groups. Here we briefly review the role of the amino-carboxylic interaction in the formation of ordered organic 2-dimensional architectures on solid surfaces. We then describe the anchoring process of carboxylic molecules on amine based SAMs we have recently reported on. New results are presented showing how multiple anchoring sites per molecule may be exploited for tailoring the molecular orientation as well as the density of the anchored molecules.

We demonstrate the possibility to achieve the doping of eumelanin thin films through K(+) incorporation during the electrodeposition of the film. K-doping changes the optical properties of the eumelanin thin films, reducing the energy gap from 1.0 to 0.6 eV, with possible implications for the photophysical properties. We have identified the doping-related occupied and unoccupied electronic states and their spectral weight using resonant photoemission spectroscopy (ResPES) and x-ray absorption at the C and N K-edges (near edge x-ray absorption fine spectroscopy, NEXAFS). All data are consistently interpreted by ab initio calculations of the electronic structure within the frame of the macrocycle model developed for the eumelanin protomolecule. Our analysis puts in evidence the intercalation of K with one specific oligomer (a tetramer composed of one indolequinone and 3 hydroquinone monomers) in correspondence of the nitrogen macrocycle. The predicted variation of the tetramer spacing is also in agreement with the recent x-ray diffraction experiments. The charge donation from K to N and C atoms gives rise to new electronic states at the top of the valence band and in NEXAFS resonances of the unoccupied orbitals. The saturation of the tetramer macrocycles leaves an excess of K that bind to N and C atoms in alternative configurations, as witnessed by the occurrence of additional spectral features in the carbon-related ResPES measurements.

Using a combination of X-ray photoelectron spectroscopy (XPS) and core level shift first principles calculations, we determine the formation of an unusual intermolecular interaction between porphyrin molecules. We show that protoporphyrin IX molecules (H2PPIX) adsorbed on Cu surfaces at low temperature (LT) form molecular adlayers stabilized by a strong (1.3 eV) tetragonal coordinated H-bond. This unconventional H-bonding involves the four nitrogen atoms in the tetrapyrrole macrocycle of one molecule, four hydrogen atoms, and one of the hydroxyl oxygen atoms from the carboxylic acid groups of an adjacent molecule. The calculations demonstrate that the corresponding fingerprint of this bond is observed in both the nitrogen XPS data, showing a unique peak, and the almost unchanged 1s core level energy of the hydroxyl oxygen atoms. We explain the formation of this bond by a charge rearrangement mechanism that includes proton sharing and migration., We acknowledge funding support from the Spanish Ministerio de Ciencia e Innovación (Grant No. FIS2010-19609-C02-01, MAT2011-26534, MAT2010-21156-C03-01, and -C03-03, PIB2010US-00652), the Basque Government (IT-257-07, IT-366-07), the ETORTEK program funded by the Basque Departamento de Industria and the Diputación Foral de Guipuzcoa. R.G.M. thanks the financial support of DIPC.

Trabajo presentado a la Conferencia NanoSpain celebrada en Santander (España) del 27 de Febrero al 1 de Marzo de 2012., The study of the chemical bond of adsorbates on and with surfaces is of particular importance for new widespread developments, from healthcare to electronics or environment. In most cases these interactions are weak and they can be considered in the context of supramolecular chemistry, which studies the organization of systems based on weak and reversible noncovalent interactions. Among them, hydrogen bond is one of the most important interactions in chemistry, biology, pharmacology, electronic, etc. In this work, we detect the formation of H bond among porphyrin molecules adsorbed on metal surfaces. Particularly, by the comparison of experimentally observed shifts of the corelevels with first principle calculations, we identify the nature of the interaction of protoporphyrin IX molecules (H2PPIX) evaporated on Cu surfaces at low-temperature and we relate them with the formation of hydrogen bonds, covalent H-N as well as NH ···O-C hydrogen bonding, between the carboxylic group and the pyrrolic ring of adjacent molecules.

We report the results of a synchrotron-based high-resolution XPS study of the interaction of L-cysteine (Cys) with well-characterized colloidal gold nanoparticles (NPs, typical size 3-4 nm), which were pre- deposited on highly oriented pyrolytic graphite and then brought into contact with the aqueous solution of Cys by drop-casting. By comparison with data previously obtained for Cys deposition on flat Au substrates (single crystals and high quality films), we demonstrate the formation of a strong Cys/NP thiolate bond. The analysis of the line shape and adsorbate-induced Au 4f core level shift, backed by simulations of the NP structure, reveals the interaction of Cys with low-coordinated Au atoms belonging to the NP edge and corners. The analysis of the N 1s core-level indicates that neutral molecules are the most abundant species. The small facet size limits the formation of extended networks of zwitterionic molecules, typical of single crystal surfaces. This study provides a spectroscopic insight into the intense poisoning effect caused by a limited amount of Cys on Au catalysts described in previous reports.

A careful choice of the surface coverage of iron phthalocyanine (FePc) on Ag (110) around the single monolayer allows us to drive with high precision both the long-range supramolecular arrangement and the local adsorption geometry of FePc molecules on the given surface. We show that this opens up the possibility of sharply switching the catalytic activity of FePc in the oxygen reduction reaction and contextual surface oxidation in a reproducible way. A comprehensive and detailed picture built on diverse experimental evidence from scanning tunnelling microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, coupled with density functional theory calculations, sheds new light on the nature of the catalytically active molecule-surface coordination and on the boundary conditions for its occurrence. The results are of relevance for the improvement of the catalytic efficiency of metallo-macrocycles as viable substitutes for platinum in the cathodic compartment of low-temperature fuel cells.

We present a combined experimental and theoretical study of the ultrathin film of Co-octaethylporphyrin (Co-OEP) molecules deposited on the Ag(110) surface. The morphological and electronic properties of this heterogeneous metallorganic interface were studied by means of scanning tunneling microscopy (STM), near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, ultraviolet photoemission spectroscopy (UPS), and density functional theory calculations (DFT). The long-range self-ordered single layer of Co-OEP was obtained by thermal desorption of the molecular multilayer. The single-layer molecules were arranged in a noncommensurate rectangular lattice aligned with the substrate high-symmetry directions. The combination of experimental techniques and numerical simulations indicated that in this configuration each molecular macrocycle is tilted with respect to the metal surface of about 15°. The strong molecular interaction with the substrate leads to the electron transfer from the metal substrate to the molecule. The direct interaction with the substrate involves mostly the Co metal center, which modifies the valence state with respect to the free Co-OEP molecules due to the hybridization between Co states and Ag bands.

6 páginas, 5 figuras.-- et al., We have studied the in situ coordination reaction of porphyrin molecules, particularly protoporphyrin IX (H2PPIX), with copper substrate atoms in ultrahigh vacuum conditions with a combination of X-ray photoelectron spectroscopy and scanning tunneling microscopy. We show that these protoporphyrin IX molecules deposited on Cu surfaces, as Cu(110) and Cu(100), form metalloprotoporphyrin IX (CuPPIX) by incorporation of Cu atoms from the surface already at room temperature. We have followed this reaction as a function of temperature and we have determined intermediate situations at lower temperatures where the physisorbed macrocycle rings present a tendency to establish hydrogen bonding between molecules., We acknowledge funding through Spanish research projects CSD2007-41, MAT2008-1497, PET2008-109, FIS2010-19609- C02-00, and BIO 2007-67523 and intramural project 200960I159. C.S.-S. is grateful to Ministerio de Educación for the AP2005-0433 FPU grant.

A antracnose causa severos danos na pós-colheita de manga. Como o controle químico tem demonstrado desvantagens, o potencial uso de óleos essenciais para o controle de fitopatógenos tem sido uma alternativa. Neste trabalho, objetvou-se avaliar a eficácia de produtos alternativos no controle da antracnose e na conservação de mangas (Mangifera indica) cv. Tommy Atkins tratado com bicarbonato de sódio diluído em água destilada, na concentração de 3% (v/v), via imersão. Como tratamento, foram utilizados os óleos essenciais de Origanum majorana, Citrus sinensis, Cymbopogon citratus e Eucalyptus citriodora, via fumigação, na dosagem de 1000 μL e água destilada via fumigação; todos por 3 minutos. Frutos da Unidade CEASA-Maringá/PR, selecionados, pesados em balança semianalítica, desinfetados em imersão por 3 minutos em solução de hipoclorito de sódio a 0,5% (v/v); foram submetidos aos tratamentos, permanecendo sob condições ambientes (26 ± 2ºC e UR 90 ± 5%). Exceto o tratamento com Citrus sinensis, que proporcionou um pH maior do que a testemunha, diferindo significativamente dos demais tratamentos que elevaram a variável. A redução da acidez em todos os tratamentos e aumentos dos sólidos solúveis totais nos frutos, sendo que o tratamento com bicarbonato de sódio proporcionou 14,42 ºBrix. O número de frutos com antracnose foi menor no tratamento com Citrus sinensis e este diferiu dos demais comprovando o efeito de espécies do gênero Citrus como antifúngicos. O uso de óleos essenciais como o de Citrus sinensis controlou a antracnose e manteve a qualidade dos frutos. The anthracnose causes severe damages to the mango post-harvest. As chemical control has shown disadvantages, the potential of use of essential oils has been an alternative for the phytopathogen control. The objective of the present work was to evaluate the efficacy of alternative products in the anthracnose control and in the conservation of mangos (Mangífera mandica) cv. Tommy Atkins treated with sodium bicarbonate diluted in distilled water, concentration of 3% (v/v), through immersion. For the treatment, the essential oils of Origanum majorana, Citrus sinensis, Cymbopogon citratus and Eucalyptus citriodora were used through fumigation, in the dosage of 1000 μL and distilled water through fumigation; all for 3 minutes. Mango fruits of the Unity CEASA-Maringá/PR, selected, weighed in a semi-analytical scale, disinfected by immersion of 3 minutes in a solution of sodium hypochlorite to 0.5% (v/v); rinsed in running water and dried. They were submitted to the treatments under ambient conditions (26 ± 2ºC and RH 90 ± 5%). Except for the treatment of Citrus sinensis, that resulted in a pH larger than the witness, significantly differing from the treatments that elevate the variable. There was reduction of the acidity in all of the treatments and increment of TSS in the fruits and with sodium bicarbonate provided 14.42 º Brix. The number of fruits with anthracnose was smaller in those treated with Citrus sinensis and this differed from the others, proving the effect of Citrus as fungitoxic. The use of essential oils such as that obtained from Citrus sinensis controlled the anthracnose and maintained the quality of the fruits.

The in situ formation of prototypes of complex hybrid organic structures gives the opportunity to characterize their morphologic and spectroscopic properties, a mandatory step toward the development of more reliable and efficient organic devices. In this context, a proper functionalization of the substrate’s surface is required for the linkage of small molecules or proteins. We report here how thin films of cysteamine have been successfully assembled on Au(111) by evaporation in ultra high vacuum conditions. The molecular orientation has been investigated by means of X-ray absorption spectroscopy. Both monolayer and multilayered films of cysteamine have been characterized by means of high-resolution photoemission spectroscopy. A compact, homogeneous self-assembled monolayer has been obtained, which provides the functionalization of the surface with a −NH2 linker. The investigation on the multilayer film revealed the presence of a zwitterionic cysteamine moiety.

The role of potassium in the formation of synthetic eumelanin aggregates is investigated by atomic force microscopy and soft-X-ray spectroscopy. Control over the thin film granularity is achieved by using K salts, in both drop casting and electrodeposition of eumelanin thin films. Further control over orientation is made possible by a suitable choice of the substrate: evidence of self-assembly is found for thin films deposited on gold. Finally, it is shown that the potassium content affects not only the samples morphology, but also the low-lying states in the valence band, where a transfer of spectral weight across the HOMO-LUMO gap is observed, disclosing possible applications of this multifunctional biomacromolecule.

The electronic structure of eumelanin thin films has been investigated by means of x-ray absorption and photoemission spectroscopies. The main features of the experimental data are interpreted on the basis of density-functional calculations for the isolated monomers participating to the eumelanin macromolecule. In order to single out the polymerization effects, we followed a bottom-up scaling approach to establish the minimum supramolecular level of organization that can provide a consistent spectroscopical picture of an altogether complex and highly disordered system. A tetramer macrocycle, made by three hydroquinones and one indolequinone, is found to reproduce the observed polymerization effects at the N K edge, while preserving the experimental spectral weight among the different monomers. This tetramer is different from that predicted for the synthesis from isolated monomers, providing an experimental evidence of the role of the reaction path on the stabilization of macrocycles in condensed-phase eumelanin.

The charge distribution of the defect states at the reduced ${\mathrm{TiO}}_{2}(110)$ surface is studied via a new method, the resonant photoelectron diffraction. The diffraction pattern from the defect state, excited at the $\mathrm{Ti}\mathrm{\text{\ensuremath{-}}}2p\mathrm{\text{\ensuremath{-}}}3d$ resonance, is analyzed in the forward scattering approach and on the basis of multiple scattering calculations. The defect charge is found to be shared by several surface and subsurface Ti sites with the dominant contribution on a specific subsurface site in agreement with density functional theory calculations.

International audience; The charge distribution of the defect states at the reduced TiO2110 surface is studied via a new method, the resonant photoelectron diffraction. The diffraction pattern from the defect state, excited at the Ti-2p-3d resonance, is analyzed in the forward scattering approach and on the basis of multiple scattering calculations. The defect charge is found to be shared by several surface and subsurface Ti sites with the dominant contribution on a specific subsurface site in agreement with density functional theory calculations.

We have investigated the controversy surrounding the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$ structure of self-assembled monolayers of methylthiolate on Au(111) by first principles molecular dynamics simulations, energy and angle resolved photoelectron diffraction, and grazing incidence x-ray diffraction. Our simulations find a dynamic equilibrium between bridge site adsorption and a novel structure where 2 ${\mathrm{CH}}_{3}\mathrm{S}$ radicals are bound to an Au adatom that has been lifted from the gold substrate. As a result, the interface is characterized by a large atomic roughness with both adatoms and vacancies. This result is confirmed by extensive photoelectron and grazing incidence x-ray diffraction measurements.

We measured NEXAFS spectra on both C and N K-edges of an ordered monolayer of lead phthalocyanine adsorbed onto an InSb(001) 4 × 2/c(8 × 2) substrate. We compared the spectra with the calculated density of unoccupied states of an isolated molecule. We demonstrate that molecules lay flat on the surface, determine the energy position of the lowest excited state, and show that it is site dependent. Finally, we compare the core exciton structure with the valence exciton structure previously measured by two different valence spectroscopic techniques and discuss their differences in terms of electron−nuclear and electron−hole Coulomb interactions.

We report photoelectron diffraction (PED) experiments of weakly sub-stoichiometric TiO 2 (100) rutile surfaces. Apart from standard core-level PED from the Ti-2p3/2 line, we have studied valence band PED from the defect induced Ti-3d states in the insulating band gap. For maximum yield, the latter were resonantly excited at the Ti-2p absorption edge. The PED patterns have been analyzed within the forward scattering approximation as well as by comparison with simulated PED patterns obtained in multiple scattering calculations. The analysis shows that the defect induced Ti-3d charge is mainly located on the second layer Ti atoms. © 2007 Elsevier B.V. All rights reserved.

We have investigated the controversy surrounding the (sqrt[3] x sqrt[3]) R30 degrees structure of self-assembled monolayers of methylthiolate on Au(111) by first principles molecular dynamics simulations, energy and angle resolved photoelectron diffraction, and grazing incidence x-ray diffraction. Our simulations find a dynamic equilibrium between bridge site adsorption and a novel structure where 2 CH3S radicals are bound to an Au adatom that has been lifted from the gold substrate. As a result, the interface is characterized by a large atomic roughness with both adatoms and vacancies. This result is confirmed by extensive photoelectron and grazing incidence x-ray diffraction measurements.

Burkitt's lymphoma is a highly malignant, aggressive and rapidly growing B-cell neoplasm, which has low long-term survival rates. Abdomen is the most frequent onset site of nonendemic Burkitt's lymphoma. The rapidity of volumetric doubling of this neoplasm frequently justifies an abdominal acute presentation, that may mime other less rare diseases. Symptoms are often misleading and make diagnosis difficult. The aim of this work is to report a case of a 13-year-old boy affected by terminal ileum Burkitt's lymphoma with hepatic metastasis, which initially was mistaken for acute appendicitis complicated by hepatic abscesses and, following a second surgical operation, for terminal-ileum inflammatory bowel disease. The rapidity of growth of this neoplasm justifies the finding, during the second surgical operation, of a mass that was not clinically manifested during first operation, carried out only a week ago. Clinical signs and instrumental investigations were not diagnostic, as well as the literature reports. The role of surgery remains controversial, and is usually limited to collection of specimens for histological diagnosis or to management of acute complications, as in our case report. Mostly treatment protocols are based on chemotherapy, because of the high sensibility of this neoplasm.

The charge distribution of the defect states at the reduced TiO(2)(110) surface is studied via a new method, the resonant photoelectron diffraction. The diffraction pattern from the defect state, excited at the Ti-2p-3d resonance, is analyzed in the forward scattering approach and on the basis of multiple scattering calculations. The defect charge is found to be shared by several surface and subsurface Ti sites with the dominant contribution on a specific subsurface site in agreement with density functional theory calculations.

– Fournier's gangrene is a rare pathology that generally occurs in weakened patients with chronic diseases, like diabetes, which imply tissue ischemia and even today a high mortality rate. Two cases are presented, one of which is interesting for its pathogenesis. The authors confirm that first choice treatment should be surgical associated with antiobiotics and hyperbaric oxygenation whenever possible.

– A case of epididymal leiomyoma is described and a review of literature confirms that this is rare tumour. Up to the present only 105 cases have been described. Treatment can be limited to simple enucleation by scrotal access.

2003/2004 Le recenti innovazioni scientifiche e tecnologiche hanno reso possibile la realizzazione di dispositivi su scala nanometrica che hanno guidato il trend di miniaturizzazione nelle industrie elettronica e dei semiconduttori. L 'utilizzo di interfacce molto ordinate tra due metalli, tra un metallo e un semi conduttore o tra un film organico ed un metallo, è stato dimostrato essere molto promettente per lo sviluppo di nuovi dispositivi grazie all'alta mobilità elettronica indotta dall'assenza di difetti e dall'alto grado di ordine di questi sistemi. La realizzazione di tali interfacce avviene tramite la crescita epitassiale di materiali in condizioni di ultra alto vuoto. La crescita epitassiale eterogenea è inoltre una tecnica largamente utilizzata per produrre materiali artificiali; una opportuna scelta del substrato di crescita infatti, permette di introdurre e controllare proprietà strutturali del film che si cresce e di regolarne in questo modo le proprietà elettroniche. Per questi motivi la capacità di studiare le proprietà non solo spettroscopiche ma anche strutturali di questi sistemi è diventata di fondamentale importanza negli ultimi anni. Nel presente lavoro un approccio multi-tecnica è stato applicato per ottenere una caratterizzazione completa dal punto di vista strutturale e morfologico di alcuni sistemi presi come esempio. I film sottili considerati sono stati studiati per mezzo della diffrazione a raggi X ad incidenza radente (GIXRD), diffrazione di fotoelettroni (PED), spettroscopia di assorbimento vicino soglia (NEXAFS), diffrazione di atomi di elio (HAS) e diffrazione di elettroni a bassa energia (LEED). Il lavoro è stato eseguito presso la linea di luce ALOISA del sincrotrone ELETTRA di Trieste. Viene riportata una breve introduzione alle tecniche sperimentali utilizzate. Due esperimenti su sistemi semplici vengono esposti per descrivere l'applicazione delle tecniche GIXRD (la determinazione delle proprietà strutturali della ricostruzione l x2 della superficie Au(ll 0)), PED e NEXAFS (determinazione dell'orientazione del gruppo CN sulla superficie Pd(llO)) e di come esse possono venire utilizzate sulla linea ALOISA. Nel caso di sistemi più complessi, l'utilizzo simultaneo di più tecniche è necessario per una caratterizzazione completa. Due esempi in questo senso vengono riportati nella presente tesi: l. Crescita di un film di N i sulla superficie Pd(l 00) I film metallici sottili, quando cresciuti su substrati opportuni, possono presentare proprietà chimiche e magnetiche inusuali, date dalle distorsioni strutturali indotte dal substrato. Uno studio strutturale di questi sistemi è necessario per otteneme una caratterizzazione completa. Nel caso del Ni su Pd(lOO), nelle prime fasi della deposizione gli atomi di Ni formano un reticolo di tipo fcc (cubico a facce centrate) distorto, con il parametro laterale pari a quello del substrato (fase pseudomorfa). Precedenti studi PED suggeriscono che una transizione strutturale di fase avviene quando il film raggiunge uno spessore di 9-12 strati atomici. A queto stadio il film si suppone assumere la struttura fcc tipica per il Ni. Noi abbiamo usato le tecniche GIXRD e PED per caratterizzare l'evoluzione delle due fasi in funzione dello spessore del film. Uno spessore critico di 10 strati atomici è stato determinato per l'inizio della transizione alla fasefcc. Le misure GIXRD hanno inoltre messo in evidenza come la transizione, caratterizzata da un forte rimescolamento dei due metalli all'interfaccia, proceda con una crescita laterale di domini di Nifcc a spese della fase pseudomorfa. I film di metallo-ftalocianine sono tra i semi conduttori organici più promettenti per applicazioni in elettronica, celle solari, sensori di gas. Le loro proprietà di trasporto possono essere migliorate ottimizzando le proprietà morfologiche, che dipendono dalla struttura dell'interfaccia con il substrato sui cui vengono cresciuti; per questo motivo lo studio dei primi stadi di deposizione della CuPe è rilevante per possibili applicazioni. Noi abbiamo studiato la struttura di un film sottile di CuPe su Au(llO) con le tecniche HAS, LEED, NEXAFS e GIXRD in funzione dello spessore, nell'intervallo tra O e 2 strati molecolari. Abbiamo evidenziato come diverse ricostruzioni della superficie vengono indotte dall'interazione molecole-substrato al variare dello spessore del film. In particolare due fasi con due diverse ricostruzioni lungo la direzione [l 00] del substrato sono state identificate: una ricostruzione x5 è presente a ricoprimento minore di uno strato molecolare; quando il primo strato molecolare del film è formato appare infine una ricostruzione x3. Misure GIXRD hanno permesso di determinare la struttura della cella x3 del substrato, che è presente in entrambe le fasi ed è accompagnata nella fase x5 da celle x2 residue della ricostruzione della superficie pulita. L'utilizzo di due tecniche sensibili in modo diverso alla superficie come HAS e LEED ha permesso di distinguere tra il grado di ordine del substrato e quello delle molecole del film; mentre allo spessore di uno strato molecolare il film è parzialmente disordinato, il substrato presenta ordine a lungo raggio. Grazie agli spettri NEXAFS si è determinata l'orientazione della molecola rispetto al substrato. E' stata misurata un'inclinazione di 25 gradi del piano molecolare rispetto alla superficie, consistente con la distorsione asimmetrica della struttura della cella x3 trovata con le misure GIXRD. The semiconductor and electronic industry has seen a remarkable miniaturization trend driven by many scientific and technologic innovations in which the device fabrication and control on the nanometric lengthscales have become a fundamental issue. The experimental quest for highly ordered metal-semiconductor, metal-metal and organic-inorganic interfaces in the modem electronics is further motivated by the observed increased electric charge carrier mobility over well ordered and defect free layers, which can be produced by epitaxial film growth under Ultra-High- Vacuum conditions. Furthermore, heterogeneous epitaxy is a widely exploited technique to fabricate artificial materials, since a proper choice of the substrate allows to introduce controlled structural modifications of the growing film and to tune in this way its electronic properties. For these reasons the capability of studying not only the spectroscopic but also the structural properties of these systems has become of fundamental importance in the last years. In this work a multi-technique experimental approach has been applied to reach an exhaustive comprehension of the interface structure and morphology on a few case studies. Thin films have been studied by means of Grazing Incidence X-Ray Diffraction (GIXRD), X-ray Photoelectron Diffraction (PED), Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS), Helium Atom Scattering (HAS) and Low Energy Electron Diffraction (LEED). The thesis work has been performed at the ALOISA beamline of ELETTRA Synchrotron in Trieste. A brief review of the experimental techniques is given. Two experiments on simple systems are presented to describe the application of GIXRD (the structural determination of the l x2 missing row Au(llO) surface reconstruction) and PED and NEXAFS ( determination of the diatomic molecule CN orientation on Pd(llO) substrate) techniques and their implementation in the experimental apparatus of ALOISA. In the case of more complex systems, a complete structural characterization requires the simultaneous use of most of the above introduced techniques. Two case studies are reported in this thesis.l. Ni film growth on Pd(lOO) surface. Thin metallic films, when grown on suitable substrates can display unusual chemical and magnetic properties due to the strain induced by the substrate. To reach a better understanding of these heterosystems a structural characterization is needed. In the case of Ni on Pd(OOl), in the early stages of deposition, Ni atoms forma tetragonally strained fcc phase with the same laterallattice spacing of the substrate (pseudomorphic phase). Previous PED measurements suggested a structural transition occurring when the film thickness exceeds approximately 9-121ayers. At this stage the film was supposed to transform into its bulk-like Ni fcc structure. We have used GIXRD and PED to fully characterize the evolution of the two phases as a function of the thickness. A critical value of l O layers has been determined as the onset for the transition to the bulk phase. The morphology and the distribution of the two species of the system has been determined. GIXRD scans analysis puts in evidence how the transition, accompanied by a strong increase of the intermixing at the Ni/Pd interface, proceeds by the lateral growth of the Ni fcc domains at the expense of the pseudomorphic phase. 2.The structural characterization of a thin Copper-Phthalocyanine (CuPc) fùm grown on Au(llO) surface. Metal-Phthalocyanines films are among the most promising organic semiconductors devices for applications in electronics, solar celis, gas sensors. Their transport properties can be improved by optimizing the film morphology, which depends on the interface structure; for this reason the study of the early stages of deposition of CuPc on metals is relevant for possible applications. W e have studied the structure of a thin Cu-Pc film on the Au(llO) surface by means of HAS, LEED, NEXAFS and GIXRD as a function of thickness in the 0-2 monolayer range. W e have shown how different reconstructions are induced by the interaction between the molecules and the substrate as a function of the film thickness. In particular, two phases have been studied displaying different reconstructions along the [l 00] direction of the surface: a x5 reconstruction is present in the submonolayer range; at the monolayer coverage a x3 phase appears. GIXRD measurements allowed to determine the structure of the x3 cell which is present in the both phases and is accompanied by residua! x2 cell of the clean surface in the x5 phase. The use of two differently surface sensitive techniques · such as HAS and LEED allowed to distinguish between the order of the substrate and the organic layer; while the molecular film is partly disordered at the monolayer stage, the substrate presents well defined long range order. The NEXAFS spectra determine the molecules orientation with respect to the substrate. A tilt angle of about 25 degrees between the molecular plane and the surface in the x3 phase has been determined, consistent with an asymmetric distortion of the structure of the x3 cell. XVII Ciclo 1974 Versione digitalizzata della tesi di dottorato cartacea.