Time filter

Source Type

Lopez-Garcia M.,CSIC - Institute of Materials Science | Galisteo-Lopez J.F.,CSIC - Institute of Materials Science | Lopez C.,CSIC - Institute of Materials Science | Garcia-Martin A.,Imm Institute Microelectronica Of Madrid
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We present a study on the ability of two-dimensional close-packed arrays of submicron dielectric spheres to confine electromagnetic radiation. Substrates having different nature, either dielectric or metallic, are considered, and the evolution of the strong spatial redistribution of the total field intensity is monitored by means of numerical simulations. The physical origin of the different modes of the system is further studied by measuring the optical response of the hybrid structures and reproducing it with an analytic effective medium model. The study evidences that the use of metallic substrates provides the best scenario for enhancing light-matter interaction in this kind of system, pointing out that the hybrid modes arising from the combination of periodic dielectric lattices and metallic substrates cannot be treated as purely photonic or plasmonic. © 2012 American Physical Society. Source

Rollinger M.,University of Kaiserslautern | Thielen P.,University of Kaiserslautern | Melander E.,Uppsala University | Ostman E.,Uppsala University | And 6 more authors.
Nano Letters | Year: 2016

We reveal an explicit strategy to design the magneto-optic response of a magneto-plasmonic crystal by correlating near- and far-fields effects. We use photoemission electron microscopy to map the spatial distribution of the electric near-field on a nanopatterned magnetic surface that supports plasmon polaritons. By using different photon energies and polarization states of the incident light we reveal that the electric near-field is either concentrated in spots forming a hexagonal lattice with the same symmetry as the Ni nanopattern or in stripes oriented along the Γ-K direction of the lattice and perpendicular to the polarization direction. We show that the polarization-dependent near-field enhancement on the patterned surface is directly correlated to both the excitation of surface plasmon polaritons on the patterned surface as well as the enhancement of the polar magneto-optical Kerr effect. We obtain a relationship between the size of the enhanced magneto-optical behavior and the polarization and wavelength of optical excitation. The engineering of the magneto-optic response based on the plasmon-induced modification of the optical properties introduces the concept of a magneto-plasmonic meta-structure. © 2016 American Chemical Society. Source

Garcia R.,Imm Institute Microelectronica Of Madrid | Herruzo E.T.,Imm Institute Microelectronica Of Madrid
Nature Nanotechnology | Year: 2012

In atomic force microscopy a cantilever with a sharp tip attached to it is scanned over the surface of a sample, and information about the surface is extracted by measuring how the deflection of the cantilever - which is caused by interactions between the tip and the surface - varies with position. In the most common form of atomic force microscopy, dynamic force microscopy, the cantilever is made to vibrate at a specific frequency, and the deflection of the tip is measured at this frequency. But the motion of the cantilever is highly nonlinear, and in conventional dynamic force microscopy, information about the sample that is encoded in the deflection at frequencies other than the excitation frequency is irreversibly lost. Multifrequency force microscopy involves the excitation and/or detection of the deflection at two or more frequencies, and it has the potential to overcome limitations in the spatial resolution and acquisition times of conventional force microscopes. Here we review the development of five different modes of multifrequency force microscopy and examine its application in studies of proteins, the imaging of vibrating nanostructures, measurements of ion diffusion and subsurface imaging in cells. © 2012 Macmillan Publishers Limited. All rights reserved. Source

Martin J.,Imm Institute Microelectronica Of Madrid | Nogales A.,CSIC - Institute for the Structure of Matter | Martin-Gonzalez M.,Imm Institute Microelectronica Of Madrid
Macromolecules | Year: 2013

We present the simple and controllable fabrication of ordered arrays of poly(3-hexylthiophene) (P3HT) solid nanowires and hollow nanotubes by infiltrating the molten polymer into AAO nanopores at temperatures promoting partial (260 C) and complete (280 C) wetting regimes, respectively. We show that such wetting regimes (and thus the formation of nanowires or nanotubes) are associated with a different internal structure in the P3HT melt. At 260 C, the P3HT organizes into a smectic mesophase. Thus, the translational motion of the P3HT molecule through the phase-separated structure would involve an enthalpic penalty, which prevents the molecular diffusion required for achieving the complete wetting regime. Consequently, the P3HT wets the nanopores in partial wetting regime, so that solid nanowires are formed. In contrast, the melt is structurally isotropic at 280 C, which promotes the complete wetting regime, yielding nanotubes. Such a smectic mesophase is also present in P3HT confined into 350 nm in diameter pores. Furthermore, we observe the formation of a new type of nanostructure consisting of twinned nanotubes (two pores formed from one original pore) as a consequence of the appearance of a longitudinal meniscus which divided the hollow interior of the initial nanotube into two independent compartments. Lastly, we use the capillary rise of the P3HT melt along the cylindrical nanopores as a "coarse" nanoscale viscosimetry experiment for the measurement of its viscosity value under confinement. The physical behavior observed for P3HT might be extrapolated to other semiconducting polymers with similar comblike molecular architectures with applications in optoelectronics, thermoelectrics, and photovoltaics (like other poly(alkylthiophenes), polycarbazoles, polyfluorenes, polyphenylenes, etc.). © 2013 American Chemical Society. Source

Payam A.F.,Imm Institute Microelectronica Of Madrid | Ramos J.R.,Imm Institute Microelectronica Of Madrid | Garcia R.,Imm Institute Microelectronica Of Madrid
ACS Nano | Year: 2012

Figure Persented: We demonstrate that the phase contrast observed with an amplitude modulation atomic force microscope depends on two factors, the generation of higher harmonics components and the energy dissipated on the sample surface. Those factors are ultimately related to the chemical composition and structure of the surface. Our findings are general, but they specifically describe the results obtained while imaging soft materials in liquid. Molecular resolution experiments performed on a protein membrane surface in liquid confirm the theory. © 2012 American Chemical Society. Source

Discover hidden collaborations