Enrico Ciliberto

Surface and bulk study of calcium phosphate bioceramics obtained by Metal Organic Chemical Vapor Deposition

Abstract Metal Organic Chemical Vapor Deposition technique (MO-CVD) has been used to produce calcium-phosphate-based bioceramic coatings. The obtained films have been studied after treatment at different temperatures in their bulk compositions using the X-ray diffraction (XRD) and in their surface composition using the X-ray photoelectron spectroscopy (XPS) and the secondary ion mass spectrometry (SIMS). β-tricalcium phosphate and stoichiometric hydroxylapatite have been found to constitute the bulk and the surface of the coating respectively after a 2 h heating treatment at 1350°C.

Photoelectron spectra of bis-cyclopentadienyl metal dihalides

Abstract He(I) and HE(II) photoelectron spectra are reported for (η-C5H5)2MX2 (M = Ti; X = F, Cl, Br, I: M = Zr, Hf; X = Cl, Br: M = Ta; X = Cl, Br) and (η-MeC5H4)2MX2 (M = Nb, X = Cl: M = Mo; X = Cl, Br, I). A substantial variation is found in the ordering of the halogen and cyclopentadienyl ionizations, the order being dependent on the metal as well as on the halogen. The compounds may be divided into three classes, namely, those in which the electrons in cyclopentadienyl e1 orbitals ionize at a lower energy than those occupying halogen pπ orbitals, those in which halogen pπ electrons have lower ionization energy than cyclopentadienyl e1 electrons and those in which the corresponding electrons arise from extensively delocalized molecular orbitals with significant contributions from both these categories of fragment orbital.

Synthesis of aluminum oxide thin films: Use of aluminum tris‐dipivaloylmethanate as a new low pressure metal organic chemical vapor deposition precursor

Amorphous aluminum oxide thin films have been produced with low pressure metal organic chemical vapor deposition technique using the aluminum tris‐dipivaloylmethanate volatile precursor. Different carrier gases were used for the depositions. The surfaces of the films were analyzed using x‐ray photoelectron spectroscopy and secondary ion mass spectrometry. A very low content of carbon was verified when oxygen and water vapor saturated argon were used as carrier gases. A higher hydration percentage of the deposited material was verified when water vapor was present during the deposition process.

He-I and He-II excited photoelectron spectra of tetracoordinated complexes of transition metal ions with β-diketonate ligands

Photoelectron spectra of dn (n = 7, 8, 10) transition metals complexes with β-diketonate ligands are reported. In tetrahedral complexes of the zinc and cobalt elements, no evidence has been found of strong covalent metalligand interactions. In the case of square-planar complexes of d8 transition metal ions, the bonding involves covalent interaction between external ligand orbitals and more internal d subshells. In the spectrum of the complex bis(acetylacetonate)nickel(II), structures have been detected around 11.5 eV which may relate to ionization of some of the 3d subshells. Similar features are not detectable in spectra of analogous palladium and platinum complexes; smaller relaxation energies in the ion states are, probably, responsible for this behaviour.

The electronic structure of hydrotris(1-pyrazolyl)borate ligand by He-I and He-II photoelectron spectroscopy

Abstract The He-I and He-II excited photoelectron spectra of the sodium and thallium(I) derivatives of the hydrotris(1-pyrazolyl)borate ligand are reported. Experimental criteria as well as quantum-mechanical calculations were used to assign photoelectron bands in the low ionization energy region. The spectra indicate a minor perturbation of metal ions on ligand based molecular orbitals. The results provide an adequate description of the electronic structure of the anion ligand itself.

Photoelectron spectroscopy of f-element organometallic compounds II. Tricyclopentadienyl derivatives of uranium(IV) and thorium(IV)

Abstract The photoelectron spectra of some cyclopentadienyI derivatives of uranium(IV) and thorium(IV), namely (C 5 H 5 ) 3 ThCl, (C 5 H 5 ) 3 UCl, (C 5 H 4 CH 3 ) 3 ThCl, (C 5 H 4 CH 3 ) 3 UCl, (C 5 H 4 CH 3 ) 3 UBr and (C 5 H 4 CH 3 ) 3 UBH 4 , are reported the metal 5 f ionization has been detected in all the uranium derivative spectra and a simple molecular orbital scheme qualitatively accounts for the number and position of the observed low energy bands.

Photoelectron spectroscopy of ƒ-element organometallic complexes: VII. Studies of di-cyclopentadienyluranium(IV) complexes containing tetrahydroborate, amido, pivalate and dithiocarbamate ligands☆

Photoelectron spectroscopy (p.e.s.) has had a remarkable impact on studies of the electronic structure of every kind of molecule since 1968. Its role has been confirmatory with respect to molecular orbital (MO) models and has presented a continuous stimulus for improvements of MO theoretical approaches.Abstract A study of gas phase photoelectron spectra of a series of U(η5-C5H5)2X2 (X = BH4, NEt2 O2CC(CH3)3, S2CNEt2) complexes has revealed changes in the sequence of upper filled molecular orbitals along the series. In all cases the first ionization event corresponds to removal of uranium 5ƒ electrons. In the case of X = NEt2, the next highest occupied ligand-based MO is an almost pure N2p lone pair, but in the other complexes this MO is π-ring in nature. The observations are consistent with the higher reactivity of the amido complexes toward molecules containing polar double bonds or acidic hydrogens and with the greater labilities of the UCp bonds in the other complexes.

The electronic structure of η5-pentamethylcyclopentadienyl complexes of group IV elements from He(I) and He(II) photoelectron spectroscopy

Abstract The bonding between the pentamethylcyclopentadienyl ligand and the Group IV elements germanium and tin has been studied by photoelectron spectroscopy. Despite the bent structures, the complexes exhibit photoelectron spectral patterns similar to those expected for a higher symmetry ( D 5 d ). There is no unambiguous evidence for the involvement of metal p subshells in the metal-ring bonding. The high ionization energies associated with ns 2 ( n = 4,5) electrons are indicative of a pronounced “inertness” of the metal lone pair and, therefore, of almost ionic metal-ligand bonding character.

Scanning ion microscopy (SIM) and secondary ion mass spectrometry (SIMS) of early iron age bronzes

Scanning ion microscopy (SIM) and secondary ion mass spectrometry (SIMS) have been used to study an Early Iron Age bronze bracelet (armilla) found in the Necropolis of Chiavari (Genoa). Ion induced secondary electron images of the longitudinally sectioned armilla have been compared with the secondary ion images obtained over the same area. A pronounced segregation of chlorine and sulphur has been observed at the corroded grain boundaries while inclusions of iron and lead, overlapped with sulphur and chlorine, respectively, has been observed inside the grains.

Investigation of the electronic structure of 2-(acetylamino)prop-2-enoic acid (N-acetyldehydroalanine) by HeI and HeII photoelectron spectroscopy

HeI and HeII excited photoelectron spectra of N-acetyldehydroalanine (2-acetylaminoprop-2-enoic acid) are presented and discussed. Assignments are proposed by comparison with acetamide and acrylic acid and by analysis of the relative band intensities in the two spectra. The major perturbation with respect to the reference molecules arises from the interaction between the acetamido- and vinyl groups.