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Donostia / San Sebastián, Spain

Ramirez M.,University of Chile | Ramirez M.,Chilean Center of Nanosciences and Nanotechnology | Rogan J.,University of Chile | Rogan J.,Chilean Center of Nanosciences and Nanotechnology | And 6 more authors.
Zeitschrift fur Physikalische Chemie | Year: 2016

We characterize, by means of the definition of a generalized distance, the differences and similarities between binary nanoclusters. To define analytically, and to compute numerically this distance, we have generalized an original concept that was introduced for pure clusters. Since the diversity of cluster conformations grows exponentially with their size, and becomes even larger when the cluster atoms are of more than one species, we limit our attention to small ones. Thus, to illustrate and analyze our distance definition we characterize the Lennard-Jones (LJ) minimum energy conformations of two- and three-dimensional (2D and 3D) binary clusters, for 5 ≤ N ≤ 12, where N is the number of atoms of the cluster. In addition, when varying the LJ potential parameters, we find that the number of minima decreases as the range of the potential of one of the species is increased, and confirm that minimal energy conformations adopt a well defined core-shell configuration. © 2016 Walter de Gruyter Berlin/Boston 2016. Source


Zhang P.,Autonomous University of Madrid | Feist J.,Autonomous University of Madrid | Rubio A.,University of the Basque Country | Rubio A.,Scientific Development Center | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We present an ab initio study of the hybridization of localized surface plasmons in a metal nanoparticle dimer. The atomic structure, which is often neglected in theoretical studies of quantum nanoplasmonics, has a strong impact on the optical absorption properties when subnanometric gaps between the nanoparticles are considered. We demonstrate that this influences the hybridization of optical resonances of the dimer, and leads to significantly smaller electric field enhancements as compared to the standard jellium model. In addition, we show that the corrugation of the metal surface at a microscopic scale becomes as important as other well-known quantum corrections to the plasmonic response, implying that the atomic structure has to be taken into account to obtain quantitative predictions for realistic nanoplasmonic devices. © 2014 American Physical Society. Source


Stella L.,Nano Bio Spectroscopy Group | Stella L.,Scientific Development Center | Stella L.,Kings College London | Zhang P.,Autonomous University of Madrid | And 5 more authors.
Journal of Physical Chemistry C | Year: 2013

Semiclassical nonlocal optics based on the hydrodynamic description of conduction electrons might be an adequate tool to study complex phenomena in the emerging field of nanoplasmonics. With the aim of confirming this idea, we obtain the local and nonlocal optical absorption spectra in a model nanoplasmonic device in which there are spatial gaps between the components at nanometric and subnanometric scales. After a comparison against time-dependent density functional calculations, we conclude that hydrodynamic nonlocal optics provides absorption spectra exhibiting qualitative agreement but not quantitative accuracy. This lack of accuracy, which is manifest even in the limit where induced electric currents are not established between the constituents of the device, is mainly due to the poor description of induced electron densities. © 2013 American Chemical Society. Source


Varas A.,University of the Basque Country | Varas A.,Scientific Development Center | Garcia-Gonzalez P.,Scientific Development Center | Garcia-Gonzalez P.,Autonomous University of Madrid | And 4 more authors.
Journal of Physical Chemistry Letters | Year: 2015

We present an ab initio study of the anisotropy and atomic relaxation effects on the optical properties of nanoparticle dimers. Special emphasis is placed on the hybridization process of localized surface plasmons, plasmon-mediated photoinduced currents, and electric-field enhancement in the dimer junction. We show that there is a critical range of separations between the clusters (0.1-0.5 nm) in which the detailed atomic structure in the junction and the relative orientation of the nanoparticles have to be considered to obtain quantitative predictions for realistic nanoplasmonic devices. It is worth noting that this regime is characterized by the emergence of electron tunneling as a response to the driven electromagnetic field. The orientation of the particles not only modifies the attainable electric field enhancement but can lead to qualitative changes in the optical absorption spectrum of the system. (Graph Presented). © 2015 American Chemical Society. Source

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