Gold Nanorod Plasmon Resonance Damping Effects on a Nanopatterned Substrate

Abstract

Substrate properties might significantly influence the scattering spectra of supported plasmonic nanoparticles because of different damping mechanisms. In this work, indium tin oxide substrates are modified by the combination of nanosphere lithography and ion-bombardment to create a nanopattern with sharp boundaries between the irradiated and masked regions. The single-particle scattering spectra of gold nanorods distributed over the nanopattern are investigated in detail. For nanorods located purely on either the masked or implanted areas, the spectra can be adequately interpreted in terms of a classical damped harmonic oscillator model, taking the chemical interface damping into account. When the particles overlap the masked and irradiated areas, however, markedly a different behavior is found depending on the actual arrangement. For the rods experiencing a symmetric inhomogeneity (i.e., by bridging between two masked regions), damping varies smoothly with the extent of substrate inhomogeneity. For the asymmetric case (rods overlapping the boundary between the implanted and masked zones), a sudden increase of the damping is found, which is rather independent on the specific extent of substrate inhomogeneity. Comparing the damping variations with the related intensity changes indicates that substrate inhomogeneity at such length scales results in a different behavior than predicted by the classical damped harmonic oscillator model applied for nanoparticles encapsulated or homogeneously surrounded by molecular coatings.

Gold Nanorods: The Most Versatile Plasmonic Nanoparticles

“…The optical properties of Au NRs and Au-NR-based systems are also related to the substrates where they reside (Figure c). − The contact between Au NRs and planar substrates is a line contact, enabling intermediate interaction strengths between those resulting from point contact (Au NSs) and face contact (Au nanoplates). Substrates can be classified into two categories according to their different effects on the optical responses of Au NRs or Au-NR-based systems, namely, dielectrics, such as silica, and conductors, such as Au.…”

Tuning Plasmonic Resonance Damping through Interfacial Defects

“…The resonant peak redshift indicates that the substrate's effective refractive index increases after Ar + ion irradiation. 27 The broader linewidth of the scattering spectra indicates a faster relaxation rate of the LSPR modes. These experimental results show a dramatic coupling between the plasmon resonances and substrate materials.…”

“…Therefore, ion irradiation can drastically modify the property of materials and result in a significant damping effect. 27,39 Then, we measured dozens of single nanoparticles on the same substrate to verify the relationship between the plasmon relaxation rates and the substrate interface. Fitting the scattering spectra with the Lorentz function, 21 we counted and compared the linewidths (representing the total LSPR damping rate) and the resonance peak of individual GNRs in the irradiated and unirradiated regions.…”

“…In 2018, Zolnai et al studied the variation of damping and scattering intensity due to substrate nanoscale inhomogeneity. 27 They fabricated a nanopattern substrate with sharp boundaries by combining nanosphere lithography and ion-bombardment. The singleparticle scattering spectra of GNRs depend on the actual configurations, and the experimental results were not consistent with those predicted by the classical damped harmonic oscillator model.…”

Mapping and Imaging of Thin Films on Large Surfaces

“…The damping variations with the related intensity changes can indicate the substrate inhomogeneity at nanometer length scales. [ 34 ]…”