title: Effect of the dielectric properties of substrates on the scattering patterns of gold nanorods.
abstract: Understanding the electromagnetic interactions between plasmonic noble metal nanocrystals and different substrates is very important because a number of plasmon-based devices and applications, such as chemical and biological sensing, metamaterials, subwavelength waveguides, plasmon-enhanced photovoltaic cells, plasmon-enhanced spectroscopy, and photoswitches, require the attachment of metal nanocrystals onto various substrates. In this study, we focused on the effect of the dielectric properties of substrates on the far-field scattering patterns of supported Au nanorods. Seven types of substrates, including metals, semiconductors, and insulators, were examined. The far-field scattering patterns from individual Au nanorods were found to exhibit a doughnut shape when the modulus of the dielectric constant of the substrate is above ∼7, while they appear as solid bright spots when the modulus is below ∼7. This finding was validated by numerical electrodynamic calculations. Moreover, the doughnut-shaped scattering patterns are very sensitive to the spacing between the nanorod and substrate. For the nanorods supported on silicon wafers, when the spacing is increased above ∼14 nm, the scattering patterns change from the doughnut shape to the solid bright spot. These results will be useful for the understanding of the plasmonic properties of noble metal nanocrystals supported on substrates and the development of a number of plasmon-based optical and optoelectronic devices at different size scales.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
authors.forename: Huanjun
authors.initials: H
authors.lastname: Chen
authors.forename: Tian
authors.initials: T
authors.lastname: Ming
authors.forename: Shouren
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhao
authors.initials: Z
authors.lastname: Jin
authors.forename: Baocheng
authors.initials: B
authors.lastname: Yang
authors.forename: Jianfang
authors.initials: J
authors.lastname: Wang
mesh_terms: D004563:Electrochemistry / Q000379:methods; D006046:Gold / Q000737:chemistry*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D055095:Optics and Photonics; D010984:Platinum / Q000737:chemistry; D011789:Quantum Theory; D012542:Scattering, Radiation; D012825:Silicon / Q000737:chemistry; D020349:Surface Plasmon Resonance; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D010984:Platinum; D006046:Gold; D014025:Titanium; D012825:Silicon