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  1. Article: Cysteine Adsorption on Twisted-Bilayer Graphene

    Hidalgo, Francisco / Rubio-Ponce, Alberto / Noguez, Cecilia

    Journal of physical chemistry. 2021 Dec. 01, v. 125, no. 49

    2021  

    Abstract: Using density functional theory, we study the adsorption of cysteine molecules on the monolayer, AB bilayer, and bilayer graphene with β = 32.20°, 27.79°, and 5.08° as twist-angles. Considering that the adsorption takes place through three sites defined ... ...

    Abstract Using density functional theory, we study the adsorption of cysteine molecules on the monolayer, AB bilayer, and bilayer graphene with β = 32.20°, 27.79°, and 5.08° as twist-angles. Considering that the adsorption takes place through three sites defined by the three functional groups of cysteine, that is, amine, thiol, and carbonyl, over graphene, we find that adsorption energies are larger than kBT at room temperature, while the electronic properties of graphene structures remain unaffected. Also, we discussed the influence of the moiré pattern on molecule adsorption by analyzing two different regions associated with AA and AB stacking. Our results show that the adsorption energies depend on the staking region, therefore, on the twist-angle, confirming that the latter parameter can be used to tune cysteine adsorption. Besides, we discussed the feasibility of twisted-bilayer graphene as enantioselector substrate, comparing the results of l- and d-cysteine enantiomers.
    Keywords adsorption ; ambient temperature ; cysteine ; density functional theory ; enantiomers ; graphene ; thiols
    Language English
    Dates of publication 2021-1201
    Size p. 27314-27322.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021/acs.jpcc.1c08649
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Active stabilization of a pseudoheterodyne scattering scanning near field optical microscope.

    Becerril, David / Cesca, Tiziana / Mattei, Giovanni / Noguez, Cecilia / Pirruccio, Giuseppe / Luce, Marco / Cricenti, Antonio

    The Review of scientific instruments

    2023  Volume 94, Issue 2, Page(s) 23704

    Abstract: Scattering scanning near-field optical microscopes (s-SNOMs) based on pseudoheterodyne detection and operating at ambient conditions typically suffer from instabilities related to the variable optical path length of the interferometer arms. These cause ... ...

    Abstract Scattering scanning near-field optical microscopes (s-SNOMs) based on pseudoheterodyne detection and operating at ambient conditions typically suffer from instabilities related to the variable optical path length of the interferometer arms. These cause strong oscillations in the measured optical amplitude and phase comparable with those of the signal and, thus, resulting in dramatic artifacts. Besides hampering the comparison between the topography and the optical measurements, such oscillations may lead to misinterpretations of the physical phenomena occurring at the sample surface, especially for nanostructured materials. Here, we propose a stabilizing method based on interferometer phase control, which improves substantially the image quality and allows the correct extraction of optical phase and amplitude for both micro- and nanostructures. This stabilization method expands the measurement capabilities of s-SNOM to any slowly time-dependent phenomena that require long-term stability of the system. We envisage that active stabilization will increase the technological significance of s-SNOMs and will have far-reaching applications in the field of heat transfer and nanoelectronics.
    Language English
    Publishing date 2023-03-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/5.0133488
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 4' 46/112: Show issues

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  3. Article: Stability and Electronic Charge Compensation of [Ag₄₄–ₓAuₓ(SR)₃₀]⁴– Clusters

    Morera-Boado, Cercis / Hidalgo, Francisco / Noguez, Cecilia

    Journal of physical chemistry. 2019 Oct. 05, v. 123, no. 43

    2019  

    Abstract: The stability and electronic properties of [Ag₄₄–ₓAuₓ(SR)₃₀]⁴– clusters with x = 0, 12, 20, and 32, and nine thiolate ligands with aromatic and aliphatic groups are investigated using density functional theory. We found differences in the energy gaps, ... ...

    Abstract The stability and electronic properties of [Ag₄₄–ₓAuₓ(SR)₃₀]⁴– clusters with x = 0, 12, 20, and 32, and nine thiolate ligands with aromatic and aliphatic groups are investigated using density functional theory. We found differences in the energy gaps, atomic geometries, and charge distributions that depend on both the metallic composition and ligand nature. Completely different behavior for aromatic and aliphatic ligands is found when we analyze the charge density. For aromatic ligands, a charge balance between the metallic core and the sulfur atoms is observed, such that a kind of charge compensation is achieved. This charge compensation is better when x = 0 and x = 12, corresponding to clusters that have been experimentally obtained. On the other hand, aliphatic ligands do not show such charge compensation, also in agreement with the fact that these clusters have not been reported. This charge balance between metals and sulfur atoms might be useful to explain the stability of these clusters and to propose the synthesis of new clusters with aromatic ligands and different substituents, as the chiral ligands that we explore here.
    Keywords density functional theory ; energy ; ligands ; metals ; physical chemistry ; sulfur
    Language English
    Dates of publication 2019-1005
    Size p. 26633-26643.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021/acs.jpcc.9b06738
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  4. Article: Tuning Adsorption of Methylamine and Methanethiol on Twisted-Bilayer Graphene

    Hidalgo, Francisco / Noguez, Cecilia / Rubio-Ponce, Alberto

    Journal of physical chemistry. 2019 June 03, v. 123, no. 24

    2019  

    Abstract: The influence of a second graphene layer on the adsorption of methanethiol and methylamine is studied using density functional theory. Exploring different adsorption sites, we compare adsorption energies of both molecules on the monolayer, A–B stacked ... ...

    Abstract The influence of a second graphene layer on the adsorption of methanethiol and methylamine is studied using density functional theory. Exploring different adsorption sites, we compare adsorption energies of both molecules on the monolayer, A–B stacked bilayer, and three different twisted-bilayer graphene systems. Results show that both molecules are physisorbed with energies larger than room temperature on determined sites, where methylamine is stronger adsorbed than methanethiol. In A–B stacking, adsorption energies are always smaller than those found in the monolayer. However, at some relative angles between the top and bottom graphene layers, the adsorption energy increases suggesting a molecular-adsorption tuning effect. Although the electronic charge at the interlayer and vacuum regions suffer a rearrangement, there is no charge transfer between molecules and graphene layers. It is expected that these results motivate further studies of molecule adsorption using as additional parameter the relative angle in twisted-bilayer graphene.
    Keywords adsorption ; ambient temperature ; density functional theory ; energy ; graphene ; methanethiol ; methylamine
    Language English
    Dates of publication 2019-0603
    Size p. 15273-15283.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021/acs.jpcc.9b02577
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: How to control optical activity in organic-silver hybrid nanoparticles.

    Hidalgo, Francisco / Noguez, Cecilia

    Nanoscale

    2016  Volume 8, Issue 30, Page(s) 14457–14466

    Abstract: The mechanisms that originate and control optical activity in organic-metal hybrid nanoparticles (NPs) are identified using a time-perturbed density functional theory. Electronic circular dichroism (CD) is studied in terms of the intrinsic chirality of ... ...

    Abstract The mechanisms that originate and control optical activity in organic-metal hybrid nanoparticles (NPs) are identified using a time-perturbed density functional theory. Electronic circular dichroism (CD) is studied in terms of the intrinsic chirality of the ligands, the number of ligands and the induced chirality by the arrangement of the ligands on the NP. Left-handed cysteine and achiral methylthio ligands adsorbed on an icosahedral silver NP are investigated. The analysis of CD allows the identification of the spectral regions when the induced chirality by the ligand array dominates over the intrinsic chirality of the ligands, determining conditions for CD control and enlargement. These results would be significant in the discussion of experimental CD spectra of organic-metal hybrid NPs, which might allow the development of new strategies to improve the sensitivity of chiroptical spectroscopies for the identification of bio and organic molecules.
    Language English
    Publishing date 2016-08-14
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/c6nr02372j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Unfolding method for periodic twisted systems with commensurate Moiré patterns.

    Sánchez-Ochoa, F / Hidalgo, Francisco / Pruneda, Miguel / Noguez, Cecilia

    Journal of physics. Condensed matter : an Institute of Physics journal

    2019  Volume 32, Issue 2, Page(s) 25501

    Abstract: We present a general unfolding method for the electronic bands of systems with double-periodicity. Within density functional theory with atomic orbitals as basis-set, our method takes into account two symmetry operations of the primitive cell: a standard ...

    Abstract We present a general unfolding method for the electronic bands of systems with double-periodicity. Within density functional theory with atomic orbitals as basis-set, our method takes into account two symmetry operations of the primitive cell: a standard expansion and a single rotation, letting to elucidate the physical effects associated to the mutual interactions between systems with more than one periodicity. As a result, our unfolding method allows studying the electronic properties of vertically stacked two-dimensional homo- or heterostructures. We apply our method to study [Formula: see text] single-layer graphene, [Formula: see text] twisted single-layer graphene, and [Formula: see text] graphene- [Formula: see text] tungsten disulfide heterostructure with an interlayer angle of [Formula: see text]. Our unfolding method allows observing typical mini gaps reported in heterostructures, as well as other electronic deviations from pristine structures, impossible to distinguish without an unfolding method. We anticipate that this unfolding method can be useful to compare with experiments to elucidate the electronic properties of two-dimensional homo- or heterostructures, where the interlayer angle can be considered as an additional parameter.
    Language English
    Publishing date 2019-09-17
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472968-4
    ISSN 1361-648X ; 0953-8984
    ISSN (online) 1361-648X
    ISSN 0953-8984
    DOI 10.1088/1361-648X/ab44f0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Ab initio electronic circular dichroism of fullerenes, single-walled carbon nanotubes, and ligand-protected metal nanoparticles.

    Noguez, Cecilia / Hidalgo, Francisco

    Chirality

    2014  Volume 26, Issue 9, Page(s) 553–562

    Abstract: The versatility and applicability of a time-perturbed density functional method implemented within the SIESTA program package to calculate electronic circular dichroism of diverse nanoparticles is discussed. Results for nanostructures, such as fullerenes, ...

    Abstract The versatility and applicability of a time-perturbed density functional method implemented within the SIESTA program package to calculate electronic circular dichroism of diverse nanoparticles is discussed. Results for nanostructures, such as fullerenes, single-wall carbon nanotubes, as well as metallic nanoparticles composed of up to hundreds of atoms were examined by comparison with previously reported experimental and theoretical results. In all cases, the calculated electronic circular dichroism shows very good consistency with other calculations, and a remarkable agreement with experiments. It is concluded that such a high-level method provides theoretical support for the quantification, understanding, and prediction of chirality and its measurement in nanostructures. It is expected that this information would be useful to motivate further experimental studies and interpretation of optical activity in terms of electronic circular dichroism in novel nanostructures.
    MeSH term(s) Circular Dichroism ; Fullerenes/chemistry ; Ligands ; Metal Nanoparticles ; Nanotubes, Carbon
    Chemical Substances Fullerenes ; Ligands ; Nanotubes, Carbon
    Language English
    Publishing date 2014-09
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1011639-4
    ISSN 1520-636X ; 0899-0042
    ISSN (online) 1520-636X
    ISSN 0899-0042
    DOI 10.1002/chir.22348
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 2594: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
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  8. Article ; Online: Optical activity of achiral ligand SCH3 adsorbed on achiral Ag55 clusters: relationship between adsorption site and circular dichroism.

    Hidalgo, Francisco / Noguez, Cecilia

    ACS nano

    2013  Volume 7, Issue 1, Page(s) 513–521

    Abstract: The electronic circular dichroism (CD) spectra of a methyl-thiol adsorbed at different sites on an icosahedral silver nanoparticle is studied by using time-perturbed density functional theory. Despite that separately molecule and nanoparticle are achiral ...

    Abstract The electronic circular dichroism (CD) spectra of a methyl-thiol adsorbed at different sites on an icosahedral silver nanoparticle is studied by using time-perturbed density functional theory. Despite that separately molecule and nanoparticle are achiral and consequently optically inactive, the Ag(55)-SCH(3) compound emerges with a new symmetry, which may be chiral or not depending on the adsorption site and orientation of the molecule. It is found that chirality is favored when the thiol is adsorbed between two atoms of different coordination number. Chiral compounds have characteristic CD spectra in the UV-visible region, where Ag(55) shows optical absorption but SCH(3) does not; revealing that highly degenerated molecular-like electronic states of Ag(55) are modified by the presence of the molecule inducing optical activity. It is concluded that CD line-shapes and magnitude strongly depend on the site where the adsorption takes place, while its intensity is modulated by the molecule orientation.
    MeSH term(s) Circular Dichroism/methods ; Light ; Materials Testing ; Metal Nanoparticles/chemistry ; Scattering, Radiation ; Silver/chemistry
    Chemical Substances Silver (3M4G523W1G)
    Language English
    Publishing date 2013-01-22
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1936-086X
    ISSN (online) 1936-086X
    DOI 10.1021/nn3046083
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Diffractive dipolar coupling in non-Bravais plasmonic lattices.

    Becerril, David / Vázquez, Omar / Piccotti, Diego / Sandoval, Elizabeth Mendoza / Cesca, Tiziana / Mattei, Giovanni / Noguez, Cecilia / Pirruccio, Giuseppe

    Nanoscale advances

    2020  Volume 2, Issue 3, Page(s) 1261–1268

    Abstract: Honeycomb plasmonic lattices are paradigmatic examples of non-Bravais lattices. We experimentally measure surface lattice resonances in effectively free-standing honeycomb lattices composed of silver nanospheres. By combining numerical simulations with ... ...

    Abstract Honeycomb plasmonic lattices are paradigmatic examples of non-Bravais lattices. We experimentally measure surface lattice resonances in effectively free-standing honeycomb lattices composed of silver nanospheres. By combining numerical simulations with analytical methods, we analyze the dispersion relation and the near-field properties of these modes along high symmetry trajectories. We find that our results can be interpreted in terms of dipole-only interactions between the two non-equivalent triangular sublattices, which naturally lead to an asymmetric near-field distribution around the nanospheres. We generalize the interaction between the two sublattices to the case of variable adjacent interparticle distance within the unit cell, highlighting symmetry changes and diffraction degeneracy lifting associated to the transition between Bravais and non-Bravais lattices.
    Language English
    Publishing date 2020-02-11
    Publishing country England
    Document type Journal Article
    ISSN 2516-0230
    ISSN (online) 2516-0230
    DOI 10.1039/d0na00095g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Plasmonic Response of Nested Nanoparticles with Arbitrary Geometry

    Diaz-H.R, Rafael / Esquivel-Sirvent Raul / Noguez Cecilia

    The Journal of Physical Chemistry C. 2016 Feb. 04, v. 120, no. 4

    2016  

    Abstract: The plasmonic response of nanoshells with different geometries is calculated using effective medium theory (EMT). The cases of multishell nanospheres, spheroids, and nested nanocubes are investigated. The model is extended to include radiation and ... ...

    Abstract The plasmonic response of nanoshells with different geometries is calculated using effective medium theory (EMT). The cases of multishell nanospheres, spheroids, and nested nanocubes are investigated. The model is extended to include radiation and nonspherical geometries to study confocal and nonconfocal ellipsoidal nanoshells as well as the combination of nested nanospheres with nanospheroids or nanocubes. As compared with more computer-intensive methods, such as finite difference time domain method (FDTD) or discrete dipole approximation (DDA), the modified EMT gives fast and accurate results. Additionally, the model is conceptually simple allowing a direct physical interpretation of the results. This methodology is useful for experimentalists who need fast and reliable predictions of the plasmonic behavior of complex nanoparticles.
    Keywords geometry ; models ; nanoparticles ; nanospheres ; physical chemistry ; prediction
    Language English
    Dates of publication 2016-0204
    Size p. 2349-2354.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021%2Facs.jpcc.5b10109
    Database NAL-Catalogue (AGRICOLA)

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