A5011288422- Phase Equilibria and Thermodynamics
- Thermodynamic properties of mixtures
- Chemical Thermodynamics and Molecular Structure
- Carbon Nanotubes in Composites
- High-pressure geophysics and materials
- Diamond and Carbon-based Materials Research
- Graphene research and applications
- Spectroscopy and Quantum Chemical Studies
- Synthesis and Properties of Aromatic Compounds
- Crystallography and molecular interactions
- X-ray Diffraction in Crystallography
- Fullerene Chemistry and Applications
- Crystallization and Solubility Studies
- Boron and Carbon Nanomaterials Research
- Thermal and Kinetic Analysis
- Material Dynamics and Properties
- Advanced Thermodynamics and Statistical Mechanics
- Advanced Chemical Physics Studies
- Mineralogy and Gemology Studies
- Microbial Inactivation Methods
- Graphite, nuclear technology, radiation studies
- Photochemistry and Electron Transfer Studies
- Building materials and conservation
- Solid-state spectroscopy and crystallography
- Cultural Heritage Materials Analysis
Universidad Complutense de Madrid
2014-2024
Heritage Malta
2019
Faculty (United Kingdom)
2014-2016
Universidad de Oviedo
2014
Université Toulouse III - Paul Sabatier
2008
Centre Interuniversitaire de Recherche et d’Ingénierie des Matériaux
2008
Centre National de la Recherche Scientifique
2008
Universidad Rey Juan Carlos
2001
This work investigates crystal lattice, electronic structure, relative stability, and high pressure behavior of TiO2 polymorphs (anatase, rutile, columbite) using the density functional theory (DFT) improved by an on-site Coulomb self-interaction potential (DFT+U). For latter effect U parameter value (0 < 10 eV) is analyzed within local approximation (LDA+U) generalized gradient (GGA+U). Results are compared to those conventional DFT Heyd-Scuseria-Ernzehorf screened hybrid (HSE06)....
We analyze the influence of biaxial strain on double-resonance ($D$ and 2$D$) Raman bands graphite-related materials. A substantial nonlinear dependence these with is observed, evidencing a quite different effect electronic structure around K $\mathbf{\ensuremath{\Gamma}}$ points first Brillouin zone. The Gr\"uneisen parameters also analyzed discussed. suggest an application spectroscopy in systems, based frequency difference observed between $G$ $D$ (or half 2$D$ features undefective...
[n]Cycloparaphenylenes behave as molecular templates of "perfectly chemically defined" single-wall carbon nanotubes. These [n]CPP molecules have electronic, mechanical, and chemical properties in size correspondence with their giant congeners. Under mechanical stress, they form charge-transfer salts, or complexes fullerene, by one-electron concave-convex electron transfer.
In this work, we present the first study of highly compressed carbon nanohorns (CNHs).
Water thermodynamic properties are available as standards through the IAPWS-95 formulation of equation state. Among these properties, speed sound is very useful for calibrating devices and obtaining derived properties. However, values calculated in range (200 to 700) MPa more uncertain than desirable, due a lack accurate experimental data above 200 MPa. The aim this work provide complete set results water covering pressure mentioned above. Speed was determined by multiple reflections method...
Abstract Previous studies on bimetallic paddlewheel compounds have established a direct correlation between metal–metal distance and ligand torsion angles, leading to the rule that higher results in longer metal‐metal bond distances. Here, new discovery based diarylformamidinate Ru₂⁵⁺ [Ru 2 Cl(DArF) 4 ] show an opposite behavior is reported: torsions lead shorter This challenges assumption internal rotation solely impacts δ bond. By combining experimental theoretical techniques, it...
Cyclic paraphenylenes, [n]CPPs, and linear [n]LPPs, formed by n benzenes, are investigated Raman spectroscopy for = 5 to 12 density functional theory (DFT) 4 20. The information on the experimental frequencies intensities, combined with DFT computations reported X-ray diffraction structures, provides a consistent interpretation of spectra allows establishing relevant structure-property trends. Structural electronic effects such as benzene ring bending, inter-ring torsions, π-conjugation...
A series of four 1 : host-guest supramolecular complexes [n]CPPs and C(70) have been analyzed by Raman spectroscopy in the solid state complemented with analysis their spectroscopic responses under mechanical thermal stresses. By following frequency behaviour G RBM modes we found that [10]CPP [10]CPP@C(70) complex displays a more "ordered" structure. However, [11]CPP@C(70), nanoring becomes oval-shaped closer contacts poles less conformational restriction flattened region. stresses are able...
We have investigated the effect of pressure on hydrogen bonding in liquid methanol using Raman spectroscopy. Specifically, we measured OH and CO stretching modes assigned bands, agreement with recent IR crossed molecular beam experiments clusters. At about 7 to 8 kbar, note indications that intrinsic nature clusters our samples has changed. Our results provide support for extend conclusions derived from Monte Carlo simulations, explain anomalies observed by previous researchers, new insights...
Cyclic conjugation and Biradical formation in charged cycloparaphenylenes are described by Raman spectroscopy DFT.
Two distinct points on the potential energy curve (PEC) of a pairwise interaction, zero-energy crossing point and where stretching force constant vanishes, allow us to anticipate range possible distances between two atoms in diatomic, molecular moieties crystalline systems. We show that these bond-stability boundaries are unambiguously defined correlate with topological descriptors electron-density-based scalar fields, can be calculated using generic PECs. Chemical databases...
We provide evidence of a universal equation state for solids using pseudospinodal hypothesis. A simple model to estimate the curve is presented. This combined with previously reported (isothermal) volumetric [Baonza et al., Phys. Rev. B 51, 28 (1995)] yields complete applicable over whole range temperature. The resulting appears be well-behaved temperatures single reference thermodynamic solid at atmospheric pressure as input data. Comparison experimental results molar volume, bulk modulus,...
We analyse here the thermodynamic behaviour of thermal expansion coefficient for a number liquids. The purpose this work is to provide some general rules develop equations state models meeting following criteria: consistency, generality, predictive power and accuracy represent derived properties over wide ranges pressure temperature. liquids included into our analysis have been selected meet two (1) available experimental data temperature (from melting point up critical point), (2) composed...
Abstract [ n ]Cycloparaphenylenes behave as molecular templates of “perfectly chemically defined” single‐wall carbon nanotubes. These ]CPP molecules have electronic, mechanical, and chemical properties in size correspondence with their giant congeners. Under mechanical stress, they form charge‐transfer salts, or complexes fullerene, by one‐electron concave–convex electron transfer.
The purpose of this work is to provide spectroscopic evidence possible chemical pathways that took place in the formation fossil resins Class I . natural polymerization process mimicked laboratory using pure communic acids (terpene derivatives) as reactants, which were subjected controlled temperature treatment. We shall focus here on trans ‐, cis ‐ and iso‐/mirceo acid isomers, temperature‐induced reactivity discussed basis different arrangements conjugated double‐bonds moieties monomeric...
We investigated the pressure dependence of Raman frequencies and intensities D G bands double-wall carbon nanotubes under strong uniaxial conditions. Using moissanite anvils, we observed for first time evolution band extreme stress/pressure find that difference between remains constant over whole stress range. In addition, observe behave elastically up to maximum reached in our experiments, which is estimated be about 12 GPa.
Abstract A fragment of the NWA 2975 Martian meteorite, an enriched basaltic shergottite, was analysed to complete its geochemical characterisation performed 10 years ago. By this means, feasibility employed techniques in a combined way for present and future space exploration missions can be tested. For aim, Raman spectroscopy used supported by micro energy dispersive X‐ray fluorescence (μ‐EDXRF) laser‐induced breakdown (LIBS) accurate interpretation molecular elemental results. results from...
Abstract We propose a new Raman pressure scale based on the shift with of fundamental band micrometer‐sized diamonds. First, we confirmed that slope triply degenerate diamond phonon behaves in similar fashion to bulk. Our measurements were calibrated against Sm:YAG fluorescence up 5 GPa using gasketed sapphire anvil cell. The most relevant features regarding design cell are briefly outlined. Measurements performed under hydrostatic conditions 4 : 1 methanol–ethanol as pressure‐transmitting...
We recently proposed an isothermal equation of state that was successfully applied to study the high-pressure behavior solids. Later, we developed a simple model include temperature effects on state. In present work consider prediction capabilities complete in entire p-V-T surface solid. Our predictions have been compared with experimental data up pressures several GPa and temperatures between zero rather higher than those melting. also compare performance our against most successful...
We have studied the Raman features characteristics of defects generated in graphite under high stress conditions. Defects are pristine highly oriented pyrolytic by squeezing samples a high‐pressure anvil cell and monitored situ spectroscopy. On basis our measurements existing literature correlations, we conclude that vacancies grain boundaries during compression–decompression cycles, being mostly decompression stage. Our results demonstrate relative intensities D, D′, (D + D′) bands strongly...
The valence shell electron pair repulsion (VSEPR) model is a demanding testbed for modern chemical bonding formalisms. challenge consists in providing reliable quantum mechanical interpretations of how concepts such as bonds, lone pairs, electronegativity, or hypervalence influence (or modulate) molecular geometries. Several schemes have been developed thus far to visualize and characterize these effects; however, the best our knowledge, no scheme has yet incorporated analysis premises...