Vicente Timón

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council), Instituto de Estructura de la Materia, Faculty Member

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Address: Madrid, Madrid, Spain

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Gustavo Adolfo Cruz Diaz

Sun Kwok

The University of Hong Kong

Indian Institute of Science

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Papers by Vicente Timón

Modelling and irradiation experiments of cosmic dust analogues

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Methyl isocyanate ices. Solid-phase infrared spectroscopy and energetic processing of a newly discovered astrophysical molecule

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Structure and energetic processing of interstellar hydrocarbon dust analogs formed by plasma deposition

a-C:H samples (0.5 m thickness) were irradiated with a 7.9×10 12 cm-2 s-1 flux of 5 keV electron... more a-C:H samples (0.5 m thickness) were irradiated with a 7.9×10 12 cm-2 s-1 flux of 5 keV electrons at normal incidence. The decay of the 3.4 µm band was followed as a function of the deposited energy. • CASINO code predicts that in the 0.5 m, a-C:H films the 5 keV electron beam leaves practically all its energy, assuming H/C=1 and =1.2 g•cm -3 [10].

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Infrared activation of the breathing mode of methane

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Infrared spectra of solid indene pure and in water ice: implications for observed IR absorptions in TMC-1

Monthly Notices of the Royal Astronomical Society

Experimental and theoretical infrared spectra, between 4000 and 500 cm−1 (2.5–20 μm), and infrare... more Experimental and theoretical infrared spectra, between 4000 and 500 cm−1 (2.5–20 μm), and infrared band strengths of two solid phases of indene, amorphous, and crystalline, are given for the first time. The samples were generated via vapour deposition under high vacuum conditions on a cold surface. Density functional theory was employed for the calculations of the infrared (IR) spectra. For lack of previous information, a monoclinic symmetry is suggested for the theoretical crystalline phase of indene, based on the comparison of the calculated and experimental IR spectra. Assignments, based on the calculations, are given for the main indene IR absorptions. The infrared spectra of highly diluted mixtures of indene in amorphous solid water at 10 K are also provided, evidencing that the indene spectrum is not much altered by the water ice environment. These data are expected to be useful for the search of this species in the solid phase in astrophysical environments with the JWST. With...

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DFT and experimental IR spectra of adsorbed and UV-processed glycine on bentonite: a Martian study

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First principles study on the electronic structure and effect of vanadium doping of BN nanowires

Solid State Communications, Apr 1, 2010

The electronic structure and effect of vanadium doping of BN nanowires are studied by first princ... more The electronic structure and effect of vanadium doping of BN nanowires are studied by first principles calculations. For the pure nanowires, it can be found that B atoms move inwards whereas N atoms move outwards, and BN nanowires have a constant band gap about 4.08 eV with larger diameter. The above-mentioned features are in agreement with those of BN nanotubes.

Vibrations of H+(D+) in stoichiometric LiNbO3 single crystal

Journal of Chemical Physics, Sep 22, 2011

Szalay et al. J. Chem. Phys. 135, 124501 (2011) FIG. 1. The supercell employed in our modeling of... more

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ZIF-75 under Pressure: Negative Linear Compressibility and Pressure-Induced Instability

Applied sciences, Oct 15, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more

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Tentative theoretical structure and infrared spectra of methyl isocyanate ice

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Structure and Spectra of Hydrogenated Amorphous Carbon: A DFT comparison between proposed models

Carbon containing grains are widespread in the ISM and in Carbon-rich stars. Observational data a... more Carbon containing grains are widespread in the ISM and in Carbon-rich stars. Observational data are taken mainly in the IR region both in emission and in absorption. Characteristic signature of these species can be found in the 3.4 m absorption band. This band is associated with carbon hydrogen stretchings of both-CH 3 and-CH 2 subunits. CH aromatic stretching are also found in the near 3.3 m band. Along with that, bending vibrations of the aforementioned subunits are found in the region from 8 to 6 m, also in the region where we could find vibrations from other functional groups, like olefinic ones. More complex torsions and other vibrations can be found below the 10 m region. The present work is devoted to the study of the structure of two of the main HAC frameworks : one formed by small aromatic rings connected by aliphatic chains (RC=rings and chains) proposed by Dartois and coworkers [1] and the other with a graphitic like backbone with aliphatic substituents in the edges of the structure, as can be seen in the work by Steglich and coworkers [2] (SG = substituted graphite). Both proposals can be found in Figure 1. Along with the study of the structure, the study of the infrared spectra can help to elucidate the nature of the ISM observations.

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CSD 1860539: Experimental Crystal Structure Determination

An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic ... more An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Theoretical and experimental UV-VIS spectra of phyllosilicates with astronomical implications

European Conference on Laboratory Astrophysics: Gas on the rocks, CSIC, Madrid, Spain, 21-25 Nove... more

Formación De Estructuras Tipo Hielo en Filosilicatos Laminares 2: Dioctaédricos

Structural single and multiple molecular adsorption of CO 2 and H 2 O in zeolitic imidazolate framework (ZIF) crystals

Microporous and Mesoporous Materials, Dec 1, 2015

Theoretical methods are used for modelling the capture and storage of CO 2 in Zinc-Imidazolate-Fr... more Theoretical methods are used for modelling the capture and storage of CO 2 in Zinc-Imidazolate-Frameworks (ZIFs). Density functional theory (DFT) is employed to establish the structure of three ZIFs with small, medium and large cages to predict the uptake behaviour of adsorbed water and carbon dioxide. Water hydration strength and configuration inside the material are investigated within and without the presence of CO 2. CO 2 is predominantly located around the inner surface of the cages in the ZIFs type ZIFn (n=1,4,6) through single and multipoint interactions. Water shows a stronger adsorption than carbon dioxide and can play an important role in solvating the CO 2 molecules inside the porous. In the final structures, H 2 O and CO 2 do not react with the surface to produce hydroxyl groups or carbonate-like species, respectively. Both species compete for the same adsorption sites. Their maximum adsorption occurs in systems with really accessible surfaces such us ZIF6. A detailed study of the surface-accessibility of a molecule on a "Connolly Surface" is reported, were ZIFs with extra-large pores plays a major role on the adsorption process. Simulated adsorption isotherms throughout MC simulations was obtained for a single CO 2 and H 2 O in which results give a ranking for the most appropriate process conditions.

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Structural Characterization and Band Assignment of the Raman Spectra of Oxammite Mineral by Density Functional Theory

Introduction: Ammonium oxalate monohydrate mineral oxammite, (NH4)2(C2O4)·H2O is a fundamental ox... more Introduction: Ammonium oxalate monohydrate mineral oxammite, (NH4)2(C2O4)·H2O is a fundamental oxalate mineral widespread in nature [1]. Oxammite is a fundamental organic mineral that has attracted attention because it exhibits the phenomenon of negative linear compressibility (NLC) [6]. The characterization of oxalate minerals is extraordinarily important since these organic minerals are indicators of environmental events and of the presence of biological origin. These minerals are nowadays under study to investigate the possible biological activity on Mars [1-2]. The identification of these compounds is usually performed by X-Ray diffraction [3] and Raman spectroscopy [1-2]. Theoretical calculations are of great value for the study and interpretation of the results of these experimental techniques. In this work, oxammite mineral was studied by first principle calculations based on the density functional theory using plane waves and pseudopotentials [4]. The computed structure of o...

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A First-principles Study on the Electronic Structures and Magnetism of Antiperovskite Ti0.96Co0.02Fe0.02O2

Journal of the Korean Magnetics Society, Jun 30, 2008

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Infrared and Raman Vibrational Modelling of Β-C2s and C3s Compounds

SSRN Electronic Journal

Periodic DFT Study of the Thermodynamic Properties and Stability of Schoepite and Metaschoepite Mineral Phases

by FRANCISCO COLMENERO RUIZ and Vicente Timón

ACS Earth and Space Chemistry, 2018

The thermodynamic properties of schoepite and metaschoepite were obtained by means of theoretical... more The thermodynamic properties of schoepite and metaschoepite were obtained by means of theoretical solid-state methods as a function of temperature. Since the values of these properties for schoepite have not been measured experimentally, they were predicted. The computed thermodynamic functions of metaschoepite were in excellent agreement with the experimental information. These functions were used to obtain the thermodynamic properties of formation of these materials from the corresponding elements. The calculated Gibbs free energy of formation of metaschoepite was shown to be very reliable and differ from the experimental value at 800 K by only 2.0%. Besides, it extends the range of temperature in which this property is known to 0−1000 K. Then, these properties were combined with those of other important uranyl-containing materials to study the reactions of formation of schoepite and metaschoepite from uranium trioxide and the reactions of transformation of these materials into dehydrated schoepite, rutherfordine, and soddyite. Schoepite becomes unstable with respect to uranium trioxide for temperatures higher than 110°C (383 ± 27 K) and its dehydration occurs at 64°C (337 ± 44 K). The corresponding values of these temperatures for metaschoepite are 82°C (355 ± 6 K) and 5°C (278 ± 9 K), respectively. Under hydrogen peroxide free conditions, schoepite and metaschoepite were found to be less stable than rutherfordine and soddyite. The thermodynamic stability of schoepite with respect to metastudtite and studtite was then studied under different conditions of temperature and concentrations of hydrogen peroxide. Schoepite and metaschoepite have very similar thermodynamic stabilities, the first being slightly more stable than the second one. The availability of the thermodynamic properties of these minerals allowed to determine their relative thermodynamic stability with respect to a rich subset of the most relevant secondary phases resulting from corrosion of spent nuclear fuel. Schoepite and metaschoepite were found to be the first and second most stable phases under intermediate hydrogen peroxide concentrations and the second and third most stable phases under high concentrations of hydrogen peroxide, respectively.

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RF plasma production and electron processing of interstellar carbonaceous dust analogs

Modelling and irradiation experiments of cosmic dust analogues

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Methyl isocyanate ices. Solid-phase infrared spectroscopy and energetic processing of a newly discovered astrophysical molecule

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Structure and energetic processing of interstellar hydrocarbon dust analogs formed by plasma deposition

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Infrared activation of the breathing mode of methane

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Infrared spectra of solid indene pure and in water ice: implications for observed IR absorptions in TMC-1

Monthly Notices of the Royal Astronomical Society