Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons--in particular their interaction with light--can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.

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Surface plasmon subwavelength optics

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

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 emerging field of plasmonics has yielded methods for guiding and localizing light at the nanoscale, well below the scale of the wavelength of light in free space. Now plasmonics researchers are turning their attention to photovoltaics, where design approaches based on plasmonics can be used to improve absorption in photovoltaic devices, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers, and yielding new options for solar-cell design. In this review, we survey recent advances at the intersection of plasmonics and photovoltaics and offer an outlook on the future of solar cells based on these principles.

Plasmonics for improved photovoltaic devices

The theoretical concept of nonexponential electronic S1 energy relaxation in nonrandom, polychromophoric polymers has been tested experimentally by means of picosecond time‐resolved fluorescence spectroscopy. For the low‐energy, sandwich‐type excimer E2 of poly‐(N‐vinylcarbazole), p‐N‐VCz, in dilute liquid solution the fluorescence rise‐profile FE2(t), collected at λem =460 nm, has been analyzed in terms of nonconventional relaxation kinetics. A time‐dependent trapping function, k(t)=b+ct−1/2, which reflects both the ‘‘effective’’ diagonal disorder and the pronounced low dimensionality of carbazole hopping sites in the fluid regime has been used in a first attempt to model migrational sampling in a sequence of excited‐state relaxation processes. The kinetic scheme consists of a distribution of transport states {X1}, a small ensemble of energy‐relaxed monomeric chromophores X2, and a discrete state of the mobile excimer X3 (E2) coupled to X2. Exact solutions to the δ‐pulse response behavior {X1}, X2, and X3, respectively, can be found which contain typically nonexponential terms of the form of time‐dependent pre‐exponentials  Aij(t). The functional forms of  Aij(t) as well as their relevancy to picosecond and nanosecond time scales have been demonstrated by synthetic data simulation. The excimer δ‐pulse trial function based upon this scheme has been shown to recover satisfactorily the experimental data. The limitations of the model, the uncertainties of rise curve analysis, in general, and the main problems encountered in rationalizing excited state transport and trapping parameters in the presence of rotational sampling have been discussed.

Electronic energy transport in aromatic vinyl‐polymers: Nonexponential picosecond trapping in poly‐(N‐vinylcarbazole)

We present a quantitative experimental analysis of a surface plasmon polariton (SPP) interferometer relying on elliptical Bragg mirrors. By using a leakage radiation microscope, we observe oscillation fringes with unit visibility at the two interferometer exits. We study the properties of the SPP beam splitter and determine experimentally both the norm and phase of the SPP reflection and transmission coefficients.

Surface Plasmon Polariton Mach–Zehnder Interferometer and Oscillation Fringes

The spontaneous emission rate of a fluorophore provides a direct probe of the photonic local density of states at the fluorophore position. Here we exploit this capability to map the plasmonic modes of gold nanoparticles by imaging the fluorescence intensity in combined regular arrays of identical gold and fluorophore-doped polymer nanoparticles. By varying the distance between gold and polymer particles across the array, the fluorophore emission generates an optical Moir\'e pattern corresponding to a magnified spatial map of the plasmonic mode, which can be directly imaged with an optical microscope. Our results are corroborated by supplementary theoretical model calculations.

https://physik.uni-graz.at/~uxh/Publications/mnp-moire10.pdf

Superresolution Moiré Mapping of Particle Plasmon Modes

We report on near-field measurements and calculations of the optical intensity close to rod-shaped gold nanoparticles excited at a multipolar plasmon resonance. Our results reveal a distinct optical near-field pattern and show that multipolar plasmon excitation of single nanoparticles can be imaged in the near-field. The observed optical near-field patterns can be understood in a model of standing plasmon waves.

Optical near-field of multipolar plasmons of rod-shaped gold nanoparticles

The surface plasmon fields of gold nanorods with a diameter of 100 nm and lengths of 1–5 
 $$\mu$$
 m are imaged by using far-field Raman scattering of methylene blue adsorbed on the rods. When optically exciting the nanorods under total internal reflection with wave vector and electric field vector orientations along the rod axis, the plasmon field intensity along this axis is observed to be periodically modulated. This modulation is attributable to a beating of the exciting light wave and the nanorod plasmon mode. The plasmon wavelength deduced from the beat frequency is 379 nm, which is considerably smaller than the exciting laser wavelength of 647 nm. In general, Raman imaging is shown to be a powerful technique to probe local plasmon fields using far-field spectroscopy.

Franz R. Aussenegg

Papers

Electronic energy transport in aromatic vinyl‐polymers: Nonexponential picosecond trapping in poly‐(N‐vinylcarbazole)

Surface Plasmon Polariton Mach–Zehnder Interferometer and Oscillation Fringes

Superresolution Moiré Mapping of Particle Plasmon Modes

Optical near-field of multipolar plasmons of rod-shaped gold nanoparticles

Far-Field Raman Imaging of Short-Wavelength Particle Plasmons on Gold Nanorods