arXiv subjects

C. E. Roman-Velazquez

Publications and source records attributed to C. E. Roman-Velazquez.

5 recordsLinked to original sources

arXiv2006

Controlled Anisotropic Deformation of Ag Nanoparticles by Si Ion Irradiation

The shape and alignment of silver nanoparticles embedded in a glass matrix is controlled using silicon ion irradiation. Symmetric silver nanoparticles are transformed into anisotropic particles whose larger axis is along the ion beam. Upon irradiation, the surface plasmon resonance of symmetric particles splits into two resonances whose separation depends on the fluence of the ion irradiation. Simulations of the optical absorbance show that the anisotropy is caused by the deformation and alignment of the nanoparticles, and that both properties are controlled with the irradiation fluence.

cond-mat.mtrl-sci↗

arXiv2005

The role of geometry on dispersive forces

The role of geometry on dispersive forces is investigated by calculating the energy between different spheroidal particles and planar surfaces, both with arbitrary dielectric properties. The energy is obtained in the non-retarded limit using a spectral representation formalism and calculating the interaction between the surface plasmons of the two macroscopic bodies. The energy is a power-law function of the separation of the bodies, where the exponent value depends on the geometrical parameters of the system, like the separation distance between bodies, and the aspect ratio among minor and major axes of the spheroid.

quant-ph↗

arXiv2005

Optical circular dichroism of single-wall carbon nanotubes

The circular dichroism (CD) spectra of single-wall carbon nanotubes are calculated using a dipole approximation. The calculated CD spectra show features that allow us to distinguish between nanotubes with different angles of chirality, and diameters. These results provide theoretical support for the quantification of chirality and its measurement, using the CD lineshapes of chiral nanotubes. It is expected that this information would be useful to motivate further experimental studies.

cond-mat.mtrl-sci↗

arXiv2003

Casimir force between a sphere and a plane: spectral representation formalism

We develop a spectral representation formalism to calculate the Casimir force in the non-retarded limit, between a spherical particle and a substrate, both with arbitrary local dielectric properties. This spectral formalism allows one to do a systematic study of the force as a function of the geometrical variables separately from the dielectric properties. We found that the force does not follow a simple power-law as a function of the separation between the sphere and substrate. As a consequence, the non-retarded Casimir force is enhanced by several orders of magnitude as the sphere approaches the substrate, while at large separations the dipolar term dominates the force.

quant-ph↗

arXiv2002

Casimir Forces between Nanoparticles and Substrates

We study the Casimir force between a nanoparticle and a substrate. We consider the interaction of metal nanoparticles with different substrates within the dipolar approximation. We study the force as a function of the distance for gold and potassium spheres, which are over a substrate of titanium dioxide, sapphire and a perfect conductor. We show that Casimir force is important in systems at the nanometer scale. We study the force as a function of the material properties, radii of the spheres, and the distance between the sphere and the substrate.

quant-ph↗