Abstract
The growing interest in plasmonic nanoparticles and their increasingly diverse applications is fuelled by the ability to tune properties via shape control, promoting intense experimental and theoretical research. Such shapes are dominated by geometries that can be described by the kinetic Wulff construction such as octahedra, thin triangular platelets, bipyramids, and decahedra, to name a few. Shape is critical in dictating the optical properties of these nanoparticles, in particular their localized surface plasmon resonance behavior, which can be modeled numerically. One challenge of the various available computational techniques is the representation of the nanoparticle shape. Specifically, in the discrete dipole approximation, a particle is represented by discretizing space via an array of uniformly distributed points-dipoles; this can be difficult to construct for complex shapes including those with multiple crystallographic facets, twins, and core–shell particles. Here, we describe a standalone user-friendly graphical user interface (GUI) that uses both kinetic and thermodynamic Wulff constructions to generate a dipole array for complex shapes, as well as the necessary input files for DDSCAT-based numerical approaches. Examples of the use of this GUI are described through three case studies spanning different shapes, compositions, and shell thicknesses. Key advances offered by this approach, in addition to simplicity, are the ability to create crystallographically correct structures and the addition of a conformal shell on complex shapes.
Highlights
Plasmonic nanoparticles (NPs) have gained much attention in the scientific community owing to their optical properties that can be exploited for a variety of applications, ranging from sensing[1] and photocatalysis,[2] to biomedicine[3] and optical circuits.[4]
NPs of free electron metals confine light via collective electron cloud oscillations triggered by an incident oscillating electromagnetic field, giving rise to resonances known as localized surface plasmon resonances (LSPRs)
We described a MATLAB-based standalone graphical user interface (GUI) that models the shape of fcc NPs, based on the modified kinetic Wulff construction theory, and creates the required input files for the DDSCAT simulations
Summary
Plasmonic nanoparticles (NPs) have gained much attention in the scientific community owing to their optical properties that can be exploited for a variety of applications, ranging from sensing[1] and photocatalysis,[2] to biomedicine[3] and optical circuits.[4] NPs of free electron metals confine light via collective electron cloud oscillations triggered by an incident oscillating electromagnetic field, giving rise to resonances known as localized surface plasmon resonances (LSPRs). The energy and peak width of a LSPR can be tuned by controlling the composition, environment, size, and shape of the NPs, to name a few.[5,16,17] Shape is appealing, as it and predictably controls the near-field distribution around a particle, creating for instance localization around either the corners or faces in a cube[18] or tip and shaft in a rod,[19] depending on the resonance frequency. Core− shell structures may be used to prevent the oxidation of a core,[23] or occur spontaneously upon self-limiting oxidation of a metal.[7,9]
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