Tuning Plasmon Resonance in Magnetoplasmonic Nanochains by Controlling Polarization and Interparticle Distance for Simple Preparation of Optical Filters

Abstract

Magnetoplasmonic FeO-coated Ag nanoparticles (NPs) are assembled in large scale (18 × 18 mm) in order to observe unique modulation of plasmonic coupling and optical tunable application via both external magnetic field and the combination of magnetic dipole and electrostatic interactions of particle-particle and particle-substrate. These large nanochains film exhibits outstanding tunability of plasmonic resonance from visible to near-infrared range by controlling the polarization angle and interparticle distance (IPD). The enormous spectral shift mainly originated from far-field rather than near-field coupling of Ag cores because of the sufficiently large separation between them in which FeO shell acts as spacer. This tunable magnetoplasmonic film can be applicable in the field of anisotropic optical waveguides, tunable optical filter, and nanoscale sensing platform.

Helical Magnetic Field-Induced Real-Time Plasmonic Chirality Modulation

“…The MagPlas NP solution has two strong absorption peaks, which are originated from Fe 3 O 4 (420 nm) and Ag (720 nm), respectively (Figure e). The appearance of the plasmon resonance of silver NPs at a relatively longer wavelength range is attributed to the increased effective refractive index by the surrounding medium (Fe 3 O 4 shell) . In order to investigate the chiroptical effect originated only from assembled superstructures, the chiroptical effect from a single NP itself was excluded by using an achiral surfactant (citric acid) because a chiral surfactant can induce chiroptical properties even in magnetic NPs through chiral distortions of the crystal structures .…”

“…The appearance of the plasmon resonance of silver NPs at a relatively longer wavelength range is attributed to the increased effective refractive index by the surrounding medium (Fe 3 O 4 shell). 25 In order to investigate the chiroptical effect originated only from assembled superstructures, the chiroptical effect from a single NP itself was excluded by using an achiral surfactant (citric acid) because a chiral surfactant can induce chiroptical properties even in magnetic NPs through chiral distortions of the crystal structures. 36 The MagPlas NP solution without applied external magnetic field exhibits no chiroptical properties over the measured wavelength range (Figure 1f).…”

“…Magnetic field-induced self-assembly and modulation is a powerful technique, as it results in an immediate response and does not require the use of templates to produce precise self-assembly. , Magnetic nanomaterials are aligned in one-dimensional structures along the magnetic flux through magnetic dipole–dipole interactions , and display anisotropic optical properties, depending upon their aligned direction. − The majority of magnetic fields that have been used in previous related research are parallel, which cannot produce chiral structures. In order to assemble the magnetic nanomaterials into chiral structures, the asymmetric field is essential, such as a helical magnetic field ( h B ), which is structurally analogous to magnetic fields originating from celestial bodies. − On the astronomical scale, h B induces the assembly of interstellar materials, and the interaction between aligned interstellar materials and light can cause the symmetry breaking, generating polarization. − Here, we mimic the astrophysical phenomenon of h B -driven symmetry breaking of light to produce h B -assisted chiral superstructure assembly of magnetoplasmonic nanoparticles (MagPlas NPs) and to obtain dynamic chiroptical properties at the same time.…”

Exploiting Anisotropy of Plasmonic Nanostructures with Polarization Modulation Infrared Linear Dichroism Microscopy (µPM‐IRLD)

“…Structures that support multiple polarization‐dependent resonances can be applied to a variety of applications. These include polarized plasmon‐mediated surface chemistry where a surface is functionalized with different analytes using different polarizations, or polarized optical filters with distinct polarization responses . An interesting, yet under explored aspect of anisotropic nanostructures is the differential absorbance, Δ A , that is associated with the dichroic (linear or circular) properties of the structure.…”

Fabrication of Polythiophene-Supported Ag@Fe3O4 Nanoclusters and Their Utilization as Photocatalyst in Dehydrogenative Coupling Reactions

“…As of now, there is no report in the literature where supramolecular assemblies of pentacenequinone scaffold 3 appended with 3-thienyl groups at 2, 9/2, 10 positions have been developed which exhibit high affinity for Ag + and Fe 3+ ions. In comparison to the reported strategies, − this wet chemical technique is a rapid and convenient protocol for the generation of polythiophene 4 supported Ag@Fe 3 O 4 nanocomposites (Table S1 and Scheme S3). Interestingly, as prepared polythiophene 4 supported Ag@Fe 3 O 4 NCs exhibited high photocatalytic efficiency in dehydrogenative coupling for the preparation of indazoles.…”