Localized Surface Plasmon Resonance Spectroscopy of Triangular Aluminum Nanoparticles

Abstract

The localized surface plasmon resonance (LSPR) of Al nanoparticles fabricated by nanosphere lithography (NSL) was examined by UV−vis extinction spectroscopy and electrodynamics theory. Al triangular nanoparticle arrays can support LSP resonances that are tunable throughout the visible and into the UV portion of the spectrum. Scanning electron microscope and atomic force microscope studies point to the presence of a thin native Al2O3 layer on the surface of the Al triangular nanoparticles. The presence of the oxide layer, especially on the tips of the nanotriangles, results in a significant red shift in the LSPR λmax. The refractive index (RI) sensitivity of the Al triangular nanoparticle arrays in bulk solvents was determined to be 0.405 eV/RIU. Theoretical results show that the oxide layer leads to a significant decrease in this RI sensitivity compared to unoxidized triangular nanoparticles of similar size and geometry. A comparison of Al, Ag, Cu, and Au triangular nanoparticles for a similar shape and geometry show that the LSPR λmax has the ordering Au > Cu > Ag > Al, while the full width at half-maximum satisfies Al > Au > Ag > Cu.

Aluminum Nanoparticles with Hot Spots for Plasmon‐Induced Circular Dichroism of Chiral Molecules in the UV Spectral Interval

“…The field of Al NPs is developing rapidly by utilizing specialized fabrication technologies suitable for aluminum, which is highly reactive. The fabrication of Al NPs involves lithography, [26] nanosphere lithography, [27,28] and colloidal synthesis. [29,30] Colloidal suspensions of Al-NCs are conveniently realized by releasing nanocrystals from a substrate into a solution.…”

Ion irradiation synthesis of Ag–Au bimetallic nanospheroids in SiO2 glass substrate with tunable surface plasmon resonance frequency

“…We have used the effective medium approximation of Kelly et al 53 In that method, the effective dielectric constant of the medium surrounding the nanospheroids was defined as the weighted average of the dielectric constants of the substrate and of the air above the substrate, with the weight determined by the relative areas of the nanoparticle exposed to the substrate and to air. 53,54 As the dielectric constant of the SiO 2 glass substrate used in our study is 3.9, the effective dielectric constant surrounding the nanospheroids is…”

Nanoplasmonic sensing for nanomaterials science

“…We also observe spectral line-widths and optical cross-sections, which are strongly dependent on material specifi c damping processes. A number of recent studies discuss plasmonic excitations in " unconventional " plasmonic metals in more detail, e.g., Pt and Pd [18, 21 -23] , Cu [24 -26] , Al [19,27,28] , Sn [20] , Ni [29] or several of the metals [30] . Moreover, localized surface plasmons have also been demonstrated in materials like VO 2 [31] or Graphene [32] .…”

“…Al is another material for which its intrinsic LSPR was used as an in situ probe to study oxidation kinetics in ambient conditions [19,27] and in water [16] . In the fi rst study in air, the presence and growth of an oxide layer was monitored by relying on two different inherent properties of LSPR: (i) the high sensitivity to refractive index changes (caused by the growing oxide), and (ii) the high sensitivity to size and shape changes of the particles (shrinking metallic core upon oxidation, possible surface roughening, etc.).…”