Monica de Simone | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)

Papers by Monica de Simone

CRC Press eBooks, Oct 27, 2006

Chemical Physics Letters, Mar 1, 2022

Inorganic Chemistry, Feb 21, 2003

Journal of Chemical Physics, Jan 3, 2013

The electronic structure of croconic acid in the gas phase has been investigated by means of core... more The electronic structure of croconic acid in the gas phase has been investigated by means of core level and valence band photoemission spectroscopy and compared with hybrid Heyd-Scuseria-Ernzerhof density functional theory calculations. The results have been compared with the corresponding ones of the condensed phase. In the gas phase, due to the absence of hydrogen bond intermolecular interactions, the O 1 s core level spectrum shows a shift of binding energy between the hydroxyl (O–H) and the carbonyl group (C=O) of 2.1 eV, which is larger than the condensed phase value of 1.6 eV. Interestingly, such a shift decreases exponentially with the increase of the O–H distance calculated from theory. The significant differences between the gas and condensed phase valence band spectra highlight the important role played by the hydrogen bonding in shaping the electronic structure of the condensed phase.

[ Research paper thumbnail of Comparative Experimental and Theoretical Study of the Fe L2,3-Edges X-ray Absorption Spectroscopy in Three Highly Popular, Low-Spin Organoiron Complexes: [Fe(CO)5], [(η5-C5H5)Fe(CO)(μ-CO)]2, and [(η5-C5H5...](https://attachments.academia-assets.com/115428809/thumbnails/1.jpg)

Inorganic Chemistry, Apr 18, 2019

Journal of Physical Chemistry C, Dec 19, 2014

Electronic structure of 4-hydroxycyanobenzene in the gas phase, thick films, and single crystals ... more Electronic structure of 4-hydroxycyanobenzene in the gas phase, thick films, and single crystals has been investigated by X-ray photoemission spectroscopy (XPS) and near edge X-ray absorption fine structure spectroscopy (NEXAFS). We have used resonant photoemission spectroscopy (RESPES) to identify the symmetry and atomic localization of the occupied and unoccupied molecular orbitals for the free molecule. Upon condensation into a thick film, we find XPS energy shifts in opposite directions for the oxygen and nitrogen core levels, consistent with the formation of an intermolecular hydrogen bond. This interaction is also accompanied by a significant spatial distortion of the lowest unoccupied molecular orbital that is displaced from the nitrogen atom, as indicated by the RESPES measurements. Thick films and single crystals display the same dichroism in polarization dependent NEXAFS, indicating that the intermolecular hydrogen bonding also steers the molecular assembly into a preferred molecular orientation.

Physical Chemistry Chemical Physics, 2020

The work function is the parameter of greatest interest in many technological applications involv... more The work function is the parameter of greatest interest in many technological applications involving charge exchange mechanisms at the interface. The possibility to produce samples with a controlled work function is then particularly interesting, albeit challenging. We synthetized nanostructured vanadium oxides films by a room temperature Supersonic Cluster Beam Deposition method, obtaining samples with tunable stoichiometry and work function (3.7-7 eV). We present an investigation of the electronic structure of several vanadium oxides films as a function of the oxygen content via in-situ Auger, valence-band photoemission spectroscopy and work function measurements. The experiments probed the partial 3d density of states, highlighting the presence of strong V3d-O2p and V3d-V4s hybridization which influence 3d occupation. We show how controlling the stoichiometry of the sample implies a control over work function, and that the access to nanoscale quantum confinement can be exploited to increase the work function of the sample relative to the bulk analogue. In general, the knowledge of the interplay among work function, electronic structure, and stoichiometry is strategic to match nanostructured oxides to their target applications.

Journal of Physical Chemistry A, Mar 1, 2003

We report high resolution measurements of near edge X-ray absorption fine structure spectra (NEXA... more We report high resolution measurements of near edge X-ray absorption fine structure spectra (NEXAFS) at the carbon and oxygen K edges of the series of related organic molecules acetaldehyde, acetone, formic acid, methanol, dimethyl ether, and paraldehyde. The spectra are compared with previous measurements of these gases and formaldehyde and with theoretical calculations. Much more fine structure is resolved than previously, particularly at the carbon edge. The results are in good overall agreement with the theoretical predictions of Plashkevych et al. (Chem. Phys. 2000, 260, 11) that the methyl group spectrum is relatively independent of the functional groups to which it is bonded, as are the carbon and oxygen carbonyl group spectra. On the other hand, oxygen atoms in hydroxyl and ether groups are strongly influenced by neighboring atoms. All of the carbon edge spectra investigated show fine structure, and only in the case of acetone do the density of states and number of vibrational degrees of freedom begin to obscure fine detail. The term values of the strongest transitions to states of acetaldehyde and acetone at the C 1s and O 1s edges are in reasonable agreement with theoretical calculations. The splittings of the C 1s-1 3p(CH 3) and 3p(CO) Rydberg states due to the low symmetry of the molecules are 0.6-0.7 and 0.38 eV for both molecules, in good agreement with theory. Absolute values of the photoabsorption cross-section, where available in the literature, show moderate to very poor agreement with measured values.

Journal of Electron Spectroscopy and Related Phenomena, Mar 1, 2012

The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using ... more The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using synchrotron radiation, with the aim of evaluating 1H/2H tautomer population ratios. The core-electron binding energies (CEBEs) were estimated from computational results, using the delta self-consistent-field (SCF) approach. Simulated spectra were generated using these CEBEs and the results from Gaussiann (Gn, n = 1, 2 and 3) and Complete Basis Set (CBS-4M and CBS-Q) methods. Results reveal the almost exclusive predominance of the 2H-tautomer, with a 1H/2H ratio of ca. 0.12/0.88, taken from a gross analysis of the XPS C 1s spectrum, recorded at 365 K.

Organometallics, Dec 29, 2021

Nucleation and Atmospheric Aerosols, 1992

Molecular effusive beam and dispersed synchrotron radiation at SuperACO positron storage ring all... more Molecular effusive beam and dispersed synchrotron radiation at SuperACO positron storage ring allowed an investigation of the complete outer‐ and inner‐valence shells photoionization of gaseous SnCl2 for the first time. New and resonating features in the inner‐valence region were observed in the photoelectron spectrum of this molecule. Auger processes following the relaxation of Sn 4d hole in the free molecule SnCl2 were detected, analogus to those observed in atomic tin.

Journal of Chemical Physics, Jun 15, 2023

High-level studies of the singlet states of quadricyclane, including analysis of a new experiment... more High-level studies of the singlet states of quadricyclane, including analysis of a new experimental vacuum ultraviolet absorption spectrum by configuration interaction and density functional calculations

Physical Chemistry Chemical Physics, 2023

Applied Optics, Sep 4, 2014

We present the design and characterization of a double-configuration grating monochromator for th... more We present the design and characterization of a double-configuration grating monochromator for the spectral selection of extreme-ultraviolet ultrafast pulses. Two grating geometries are joined in an instrument with two interchangeable diffracting stages, both used at grazing incidence: one with the gratings in the off-plane mount (OPM), the other in the classical diffraction mount (CDM). The use of two stages gives great flexibility: the OPM stage is used for sub-50 fs time response and low spectral resolution, while the CDM stage is for 100-200 fs time response and high spectral resolution. The monochromator spectral and temporal performances have been experimentally demonstrated on a high-order laserharmonics beam line.

Journal of Physics B: Atomic, Molecular and Optical Physics, 2022

We report on the C K-edge x-ray absorption spectra and the resonant (RXES) and non-resonant (NXES... more We report on the C K-edge x-ray absorption spectra and the resonant (RXES) and non-resonant (NXES) x-ray emission spectra of ethylene, allene and butadiene in the gas phase. The RXES and NXES show clear differences for the different molecules. Overall both types of spectra are more structured for ethylene and allene, than for butadiene. Using density functional theory–restricted open shell configuration interaction single calculations, we simulate the spectra with remarkable agreement with the experiment. We identify the spectral features as being due to transitions involving localised 1s orbitals. For allene, there are distinct spectral bands that reflect transitions predominantly from either the central or terminal carbon atoms. These results are discussed in the context of ultrafast x-ray studies aimed at detecting the passage through conical intersections in polyatomic molecules.

arXiv: High Energy Astrophysical Phenomena, 2019

Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as ... more Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as XRISM and Athena, we are finally poised to answer important questions about the formation and evolution of galaxies and large-scale structure. However, we currently lack an adequate understanding of many atomic processes behind the spectral features we will soon observe. Large error bars on parameters as critical as transition energies and atomic cross sections can lead to unacceptable uncertainties in the calculations of e.g., elemental abundance, velocity, and temperature. Unless we address these issues, we risk limiting the full scientific potential of these missions. Laboratory astrophysics, which comprises theoretical and experimental studies of the underlying physics behind observable astrophysical processes, is therefore central to the success of these missions.

Journal of Instrumentation, 2018

In this contribution we present the new experimental end-station to characterize XUV diffractive ... more In this contribution we present the new experimental end-station to characterize XUV diffractive optics, such as Micro Channel Plates (MCPs) and other polycapillary optics, presently under commission at the Elettra synchrotron radiation laboratory (Trieste, Italy). To show the opportunities offered by these new optical devices for 3rd and 4th generation radiation sources, in this work we present also some patterns collected at different energies of the primary XUV radiation transmitted by MCP optical devices working in the normal incidence geometry.

High Tc Superconductors, 1989

ABSTRACT The variation of the Cu K-edge x-ray absorption near edge structure (XANES) determined b... more ABSTRACT The variation of the Cu K-edge x-ray absorption near edge structure (XANES) determined by the structural changes that accompany the loss of oxygen going from the high Tc superconductor YBa2Cu3O7 to the antiferromagnetic insulator YBa2Cu3O6 has been calculated by multiple scattering theory. The elongation of the Cu(2)-O(4) distance (between the Cu(2) in the CuO2 plane and its apical oxygen) induces the shift of the main peak in polarized XANES spectra E//c toward lower energy. The formation of the oxygen vacancies induces changes in the E ⊥ c spectra for the Cu(1) ion in the linear chains. The results are in agreement with the experimental changes of the Cu XANES spectra induced by oxygen vacancies.

Organometallics, Jun 18, 2010

ABSTRACT The first examples of gas-phase photoelectron spectra of ytterbium and lutetium complexe... more ABSTRACT The first examples of gas-phase photoelectron spectra of ytterbium and lutetium complexes are reported. Variable photon energy photoelectron spectroscopy of YbCp3 (Cp = Œ∑-C5H5) shows that f electron ionization gives ion states corresponding to both 4f12 and 4f13 configurations, whereas that of LuCp3 reveals only 4f13 ion states. Magnetic data on cryst. YbCp3 display Curie behavior between 20 and 305 K with a magnetic moment of 3.53 ŒºB. Both the photoelectron spectra and the magnetic moment are consistent with the proposal that YbCp3 has a mixed configuration ground state with the unpaired spin residing both in an f orbital and on the cyclopentadienyl ligands. [on SciFinder(R)]

Physical Chemistry Chemical Physics, 2019

The comprehensive electronic structure of a starburst molecule (m-MTDATA) is thoroughly character... more The comprehensive electronic structure of a starburst molecule (m-MTDATA) is thoroughly characterized for the first time, unveiling its good electron donor properties.