[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...

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The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). These cubes were single crystals and were characterized by a slightly truncated shape bounded by {100}, {110}, and {111} facets. The presence of PVP and its molar ratio (in terms of repeating unit) relative to silver nitrate both played important roles in determining the geometric shape and size of the product. The silver cubes could serve as sacrificial templates to generate single-crystalline nanoboxes of gold: hollow polyhedra bounded by six {100} and eight {111} facets. Controlling the size, shape, and structure of metal nanoparticles is technologically important because of the strong correlation between these parameters and optical, electrical, and catalytic properties.

http://science.sciencemag.org/content/sci/298/5601/2176.full.pdf

Shape-Controlled Synthesis of Gold and Silver Nanoparticles

We present the design for an absorbing metamaterial (MM) with near unity absorbance A(omega). Our structure consists of two MM resonators that couple separately to electric and magnetic fields so as to absorb all incident radiation within a single unit cell layer. We fabricate, characterize, and analyze a MM absorber with a slightly lower predicted A(omega) of 96%. Unlike conventional absorbers, our MM consists solely of metallic elements. The substrate can therefore be optimized for other parameters of interest. We experimentally demonstrate a peak A(omega) greater than 88% at 11.5 GHz.

Perfect metamaterial absorber.

We use optical-pump THz-probe spectroscopy to study carrier dynamics in self-assembled ErAs:GaAs nanoislands. Sub-picosecond carrier capture times are measured, indicating the potential of these devices as THz detectors comparable to low temperature grown GaAs.

Carrier dynamics in self-assembled ErAs nanoislands measured by optical-pump THz-probe spectroscopy

Supplementary document for Terahertz investigation of bound states in the continuum of metallic metasurfaces - 4844686.pdf

Josephson Plasma Resonance observed in TI 2 Ba 2 CaCu 2 O 8 Superconducting Thin Rims using Terahertz Time-Domain Spectroscopy

The first femtosecond carrier relaxation dynamics studies in heavy fermion compounds are presented. The carrier relaxation time shows a dramatic hundred-fold increase below the Kondo temperature revealing a dramatic sensitivity to the electronic density of states near the Fermi level.

https://arxiv.org/pdf/cond-mat/0201194.pdf

Carrier relaxation dynamics in heavy fermion compounds

Utilizing terahertz time domain spectroscopy, we characterized the electromagnetic response of planar Split Ring Resonators fabricated on GaAs. Optical excitation is sufficient to turn off the electric resonance demonstrating the potential of SRR terahertz switches.

Richard D. Averitt

Papers

Carrier dynamics in self-assembled ErAs nanoislands measured by optical-pump THz-probe spectroscopy

Supplementary document for Terahertz investigation of bound states in the continuum of metallic metasurfaces - 4844686.pdf

Josephson Plasma Resonance observed in TI 2 Ba 2 CaCu 2 O 8 Superconducting Thin Rims using Terahertz Time-Domain Spectroscopy

Carrier relaxation dynamics in heavy fermion compounds

Dynamical electric metamaterial response at terahertz frequencies