Showing papers on "Light scattering published in 2012"
TL;DR: A novel systematic approach to enhance underwater images by a dehazing algorithm, to compensate the attenuation discrepancy along the propagation path, and to take the influence of the possible presence of an artifical light source into consideration is proposed.
Abstract: Light scattering and color change are two major sources of distortion for underwater photography. Light scattering is caused by light incident on objects reflected and deflected multiple times by particles present in the water before reaching the camera. This in turn lowers the visibility and contrast of the image captured. Color change corresponds to the varying degrees of attenuation encountered by light traveling in the water with different wavelengths, rendering ambient underwater environments dominated by a bluish tone. No existing underwater processing techniques can handle light scattering and color change distortions suffered by underwater images, and the possible presence of artificial lighting simultaneously. This paper proposes a novel systematic approach to enhance underwater images by a dehazing algorithm, to compensate the attenuation discrepancy along the propagation path, and to take the influence of the possible presence of an artifical light source into consideration. Once the depth map, i.e., distances between the objects and the camera, is estimated, the foreground and background within a scene are segmented. The light intensities of foreground and background are compared to determine whether an artificial light source is employed during the image capturing process. After compensating the effect of artifical light, the haze phenomenon and discrepancy in wavelength attenuation along the underwater propagation path to camera are corrected. Next, the water depth in the image scene is estimated according to the residual energy ratios of different color channels existing in the background light. Based on the amount of attenuation corresponding to each light wavelength, color change compensation is conducted to restore color balance. The performance of the proposed algorithm for wavelength compensation and image dehazing (WCID) is evaluated both objectively and subjectively by utilizing ground-truth color patches and video downloaded from the Youtube website. Both results demonstrate that images with significantly enhanced visibility and superior color fidelity are obtained by the WCID proposed.
782 citations
Book•
03 Dec 2012
TL;DR: In this article, a study of DLS by macromolecular and polyelectrolyte solution is presented, which provides information about size, shape and flexibility of particles as well as offering insight concerning the nature of the interactions between particles and their environments.
Abstract: Dynamic light scattering (DLS) techniques provide information about size, shape, and flexibility of particles as well as offering insight concerning the nature of the interactions between particles and their environments. This book offers a study of DLS by macromolecular and polyelectrolyte solution
423 citations
TL;DR: It is demonstrated experimentally that a back reflector with plasmonic Ag nanoparticles can provide light-trapping performance comparable to state-of-the-art random textures in n-i-p amorphous silicon solar cells.
Abstract: Plasmonic metal nanoparticles are of great interest for light trapping in thin-film silicon solar cells. In this Letter, we demonstrate experimentally that a back reflector with plasmonic Ag nanoparticles can provide light-trapping performance comparable to state-of-the-art random textures in n-i-p amorphous silicon solar cells. This conclusion is based on the comparison to high performance n-i-p solar cell and state-of-the-art efficiency p-i-n solar cells deposited on the Asahi VU-type glass. With the plasmonic back reflector a gain of 2 mA/cm2 in short-circuit current density was obtained without any deterioration of open circuit voltage or fill factor compared to the solar cell on a flat back reflector. The excellent light trapping is a result of strong light scattering and low parasitic absorption of self-assembled Ag nanoparticles embedded in the back reflector. The plasmonic back reflector provides a high degree of light trapping with a haze in reflection greater than 80% throughout the wavelength r...
402 citations
TL;DR: An analysis of the optical properties of human skin, with particular regard to their applications in medicine, concludes that further work in the field is necessary to establish a definitive range of realistic coefficients for clinically normal skin.
Abstract: A survey of the literature is presented that provides an analysis of the optical properties of human skin, with particular regard to their applications in medicine. Included is a description of the primary interactions of light with skin and how these are commonly estimated using radiative transfer theory (RTT). This is followed by analysis of measured RTT coefficients available in the literature. Orders of magnitude differences are found within published absorption and reduced-scattering coefficients. Causes for these discrepancies are discussed in detail, including contrasts between data acquired in vitro and in vivo. An analysis of the phase functions applied in skin optics, along with the remaining optical coefficients (anisotropy factors and refractive indices) is also included. The survey concludes that further work in the field is necessary to establish a definitive range of realistic coefficients for clinically normal skin.
389 citations
TL;DR: Nanophotonics aims to find reliable solutions to enhance the absorption of light in thin films, and engineering the absorbing material at the nanoscale indeed leads to interferences that can significantly increase light absorption.
Abstract: Elaborating reliable and versatile strategies for efficient light coupling between free space and thin films is of crucial importance for new technologies in energy efficiency. Nanostructured materials have opened unprecedented opportunities for light management, notably in thin-film solar cells. Efficient coherent light trapping has been accomplished through the careful design of plasmonic nanoparticles and gratings, resonant dielectric particles and photonic crystals. Alternative approaches have used randomly textured surfaces as strong light diffusers to benefit from their broadband and wide-angle properties. Here, we propose a new strategy for photon management in thin films that combines both advantages of an efficient trapping due to coherent optical effects and broadband/wide-angle properties due to disorder. Our approach consists of the excitation of electromagnetic modes formed by multiple light scattering and wave interference in two-dimensional random media. We show, by numerical calculations, that the spectral and angular responses of thin films containing disordered photonic patterns are intimately related to the in-plane light transport process and can be tuned through structural correlations. Our findings, which are applicable to all waves, are particularly suited for improving the absorption efficiency of thin-film solar cells and can provide a new approach for high-extraction-efficiency light-emitting diodes.
343 citations
TL;DR: It is demonstrated that light scattering by all-dielectric oligomers exhibits well-pronounced Fano resonances with strong suppression of the scattering cross section, which makes them promising for future applications in nanophotonics.
Abstract: We demonstrate that light scattering by all-dielectric oligomers exhibits well-pronounced Fano resonances with strong suppression of the scattering cross section. Our analysis reveals that this type of the Fano resonance originates from the optically induced magnetic dipole modes of individual high-dielectric nanoparticles. By comparing to the plasmonic analogues, we observe that Fano resonances in all-dielectric oligomers are less sensitive to structural variations, which makes them promising for future applications in nanophotonics.
316 citations
Journal Article•
TL;DR: In this paper, the scattering of light with altered frequency has been investigated in many crystals, and much valuable information has been accumulated, and their relation to theories of solid state are clearly matters of great interest.
Abstract: Since its discovery1, early in 1928, the scattering of light with altered frequency has been investigated in many crystals, and much valuable information has been accumulated. The significance of the results and their relation to theories of solid state are clearly matters of great interest.
310 citations
TL;DR: It is shown that for moderate and large light scattering near field calculations the computer time required is reduced in comparison to some of the other methods.
Abstract: A near-field calculation of light electric field intensity inside and in the vicinity of a scattering particle is discussed in the discrete dipole approximation. A fast algorithm is presented for gridded data. This algorithm is based on one matrix times vector multiplication performed with the three dimensional fast Fourier transform. It is shown that for moderate and large light scattering near field calculations the computer time required is reduced in comparison to some of the other methods.
236 citations
TL;DR: Experimental evidence is provided that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering.
Abstract: Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.
230 citations
TL;DR: Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions and shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, and vesicle structure and transport properties.
Abstract: Nano- and microparticles have optical, structural, and chemical properties that differ from both their building blocks and the bulk materials themselves. These different physical and chemical properties are induced by the high surface-to-volume ratio. As a logical consequence, to understand the properties of nano- and microparticles, it is of fundamental importance to characterize the particle surfaces and their interactions with the surrounding medium. Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions. They have shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, molecular orientation distribution of molecules at particle surfaces in solution, interfacial structure of surfactants at droplet interfaces, acid-base chemistry on particles in solution, and vesicle structure and transport properties.
TL;DR: This work has shown that hierarchical nanostructures possessing an architecture that may provide sufficient internal surface area for dye adsorption and meanwhile may generate highly effective light scattering, make them able to create photoelectrode films with optical absorption significantly more efficient than the dispersed nanoparticles used in conventional dye-sensitized solar cells.
Abstract: Light scattering is a method that has been employed in dye-sensitized solar cells for optical absorption enhancement. In conventional dye-sensitized solar cells, large TiO2 particles with sizes comparable to the wavelength of visible light are used as scatterers by either being mixed into the nanocrystalline film to generate light scattering or forming a scattering layer on the top of the nanocrystalline film to reflect the incident light, with the aim to extend the traveling distance of incident light within the photoelectrode film. Recently, hierarchical nanostructures, for example nanocrystallite aggregates (among others), have been applied to dye-sensitized solar cells. When used to form a photoelectrode film, these hierarchical nanostructures have demonstrated a dual function: providing large specific surface area; and generating light scattering. Some other merits, such as the capability to enhance electron transport, have been also observed on the hierarchically structured photoelectrode films. Hierarchical nanostructures possessing an architecture that may provide sufficient internal surface area for dye adsorption and meanwhile may generate highly effective light scattering, make them able to create photoelectrode films with optical absorption significantly more efficient than the dispersed nanoparticles used in conventional dye-sensitized solar cells. This allows reduction of the thickness of the photoelectrode film and thus lowering of the charge recombination in dye-sensitized solar cells, making it possible to increase further the efficiency of existing dye-sensitized solar cells.
TL;DR: This work derives near field extensions of the Kerker conditions in order to determine the conditions that strongly reduce scattering in either the forward or backward directions and designs a lossless dielectric collector element whose directivity is boosted by the coherent scattering of both electric and magnetic dipoles.
Abstract: Dielectric particles supporting both magnetic and electric Mie resonances are shown to be able to either reflect or collect the light emitted by a single photon source. An analytical model accurately predicts the scattering behavior of a single dielectric particle electromagnetically coupled to the electric dipole transition moment of a quantum emitter. We derive near field extensions of the Kerker conditions in order to determine the conditions that strongly reduce scattering in either the forward or backward directions. This concept is then employed to design a lossless dielectric collector element whose directivity is boosted by the coherent scattering of both electric and magnetic dipoles.
Book•
25 Feb 2012
TL;DR: In this article, the authors present a survey of X-ray techniques and their application in computer-based data processing, as well as a list of symbols for different types of reflections.
Abstract: 1. Introduction.- 1. Motivations for Spectroelectrochemistry.- 2. Methodologies Available.- 3. Computer-Based Data Processing.- 4. The Future.- References.- 2. X-Ray Techniques.- 1. Historical Background.- 1.1. Ultrahigh Vacuum Techniques.- 1.2. X-Ray Techniques for Surface Study.- 1.2.1. Scattering Methods.- 1.2.2. Absorption Techniques.- 1.3. Neutron Scattering.- 2. Theory-The Interaction of X-Rays with Matter.- 2.1. X-Ray Scattering.- 2.2. X-Ray Absorption.- 3. Experimental Details.- 3.1. In Situ X-Ray Diffraction.- 3.1.1. X-Ray Detection Methods.- 3.1.2. X-Ray Sources.- 3.1.3. Cell Design.- 3.1.4. The Experiment.- 3.2. In Situ X-Ray Absorption Studies.- 4. Applications.- 4.1. In Situ X-Ray Diffraction.- 4.2. EXAFS Studies.- List of Symbols.- References.- 3. Photoemission Phenomena at Metallic and Semiconducting Electrodes.- 1. Introduction.- 1.1. Some General Features of Photoelectronic Emission.- 1.2. Reaction Step Models for Photoemission.- 2. Theoretical: Metals.- 2.1. Fowler's Theory for Metal/Vacuum Interfaces.- 2.2. Tunneling through the Potential Barrier.- 2.3. Quantum Mechanical Photoemission Theories for the Metal/Vacuum and Metal/Electrolyte Interfaces.- 2.4. Optical Polarization and Crystal Epitaxy Effects.- 2.5. Role of the Electrical Double Layer.- 3. Theoretical: Semiconductors.- 3.1. Kane's Theory for Semiconductor/Vacuum Interfaces.- 3.2. Gurevich's Quantum Mechanical $$ \frac{3} {2} $$ Law for In Situ Photoemission.- 3.3. Bockris and Uosaki Treatment.- 3.4. Hot Carrier Effects: The Nozik-Williams Model.- 4. Experimental Techniques.- 4.1. Choice of Scavanger and Electrolyte.- 4.2. Cell Design and Electrode Preparation.- 4.3. Optics, Apparatus, and Methods.- 5. Conclusions.- 5.1. Physical Mechanistic Studies.- 5.2. Solvated Electron Chemistry.- References.- 4. UV-Visible Reflectance Spectroscopy.- 1. Introduction.- 2. Physical Optics.- 2.1. Optical Constants.- 2.2. The Reflectivity of an Interface.- 2.3. Three-Phase System and Linear Approximation.- 2.4. Nonlocal Optics.- 3. Experimental.- 3.1. Arrangements for Determining ?R/R.- 3.2. Electrochemical Cells and Electrodes.- 4. The Metal/Electrolyte Interface.- 4.1. Electroreflectance Studies of the Metal Surface.- 4.2. Surface States at the Metal/Electrolyte Interface.- 4.3. Surface Plasmon Studies.- 4.4. Double-Layer Contributions to Electroreflectance.- 5. Chemisorption and Film Formation.- 5.1. Oxides.- 5.2. Ions and Molecules.- 5.3. Metal Adsorbates.- 5.4. Metal Film Formation.- 6. Summary and Outlook.- Appendix I.- Appendix II.- List of Symbols.- References.- 5. Infrared Reflectance Spectroscopy.- 1. Introduction and Historical Survey.- 2. Theory of Reflection-Absorption Spectroscopy.- 2.1. Propagation of an Electromagnetic Plane Wave.- 2.2. Fundamentals of Absorption Spectroscopy. Selection Rules.- 2.3. Specular Reflection. Application to Reflection-Absorption Spectroscopy. Surface Selection Rules.- 3. Experimental Techniques.- 3.1. Dispersive Spectrometers.- 3.1.1. Optical Components Used in Infrared Spectrometers Specially Designed for External Reflectance Spectroscopy.- 3.1.2. Signal Detection and Processing.- 3.1.3. Techniques for External Reflectance Spectroscopy.- 3.1.4. Internal Reflection Spectroscopy.- 3.2. Fourier Transform Infrared Spectroscopy (FTIRS).- 3.2.1. Principle of FTIR Spectrometers.- 3.2.2. Use for External Reflection Measurements.- 3.2.3. Use for Internal Reflection.- 3.3. Design of the Spectroelectrochemical Cell.- 3.3.1. Electrochemical Cells for External Reflection.- 3.3.2. Electrochemical Cells for Internal Reflection.- 3.4. Discussion of the Techniques.- 4. Applications to Selected Examples.- 4.1. General Survey.- 4.2. Adsorption of Hydrogen on Platinum in Acid Media.- 4.2.1. Why This Example?.- 4.2.2. Experimental Conditions and Data Acquisition.- 4.2.3. Interpretation of the Results.- 4.3. Adsorption of Carbon Monoxide on Noble Metals in Aqueous Media.- 4.3.1. Choice of This Example.- 4.3.2. Adsorption of CO on Platinum Electrodes.- 4.3.3. Adsorption of CO on Palladium.- 4.3.4. Infrared Bands of Adsorbed CO.- 4.4. Adsorbed Intermediates in Electrocatalysis.- 4.4.1. Chemisorption of Methanol at a Platinum Electrode.- 4.4.2. Chemisorption of Formic Acid at Platinum, Rhodium, and Gold Electrodes.- 4.4.3. Chemisorption of Ethanol at a Platinum Electrode.- 4.5. Investigations in Nonaqueous Solvents and Detection of the Intermediates Formed in the Vicinity of the Electrode Surface.- 4.5.1. Choice of Examples.- 4.5.2. Spectra of Adsorbed Species in Nonaqueous Media.- 4.5.3. Observation of Anion and Cation Radicals.- 5. Conclusions.- References.- 6. Surface-Enhanced Raman Scattering.- 1. Overview.- 1.1. Introduction.- 1.2. Light Scattering by Molecules.- 1.3. Characteristics of Surface Raman Scattering.- 1.4. The SERS Experiment.- 1.5. Active Sites and the Quenching of SERS.- 1.6. Metal-Molecule Complex.- 1.7. Theoretical Considerations.- 2. Experimental Methods.- 2.1. Introduction.- 2.2. Intensity of Detected Scattered Light.- 2.3. Laser Radiation Sources.- 2.4. Optical Setup and Depolarization Ratio Measurements.- 2.5. Electrochemical Cell, Instrumentation, and Pretreatment.- 2.6. The Monochromator and Detection System.- 3. Theory of the Electromagnetic Enhancement in SERS.- 3.1. The Electromagnetic Enhancement for Spherical Particles.- 3.1.1. Electrostatic Boundary Value Problem for a Metal Sphere.- 3.1.2. Enhancement Factors for a Spherical Geometry.- 3.2. The Electromagnetic Enhancement for a Prolate Metal Spheroid.- 3.2.1. Electrostatic Boundary Problem for a Prolate Metal Spheroid.- 3.2.2. Enhancement Factors for Prolate Spheroidal Geometry.- 3.3. Electrodynamic Effects.- 4. The Chemical Enhancement in SERS.- 4.1. Normal Raman Scattering.- 4.2. Resonance Raman Scattering.- 4.3. Herzberg-Teller Corrections.- 4.4. Surface-Enhanced Raman Spectroscopy: A Charge Transfer Theory.- 5. Overall Enhancement Equations for Surface Raman Scattering.- 5.1. Effect of Concentration in a Pure EM Surface Effect.- 5.2. Overall Enhancement Equation for SERS.- 5.3. Enhanced Scattering in a Surface-Enhanced Resonance Raman Process.- 6. Symmetry Considerations for SERS.- 6.1. Vibrational Selection Rules for SERS.- 6.2. Surface Selection Rules in SERS.- 7. Effects of Electrode Potential in SERS.- 7.1. Effect of Electrode Potential on SERS Intensities.- 7.1.1. Charge Transfer Resonance Dependence on Potential and Excitation Frequency.- 7.1.2. Electric Field Effects.- 7.2. SERS Intensities as a Function of Potential in the Presence of an Electrode Reaction.- 8. Application of SERS to Chemical Systems.- 8.1. Neutral Nitrogen-Containing Molecules on Ag and Cu Electrodes.- 8.2. Anions and the Effect of Supporting Electrolyte at Ag Electrodes.- 8.3. Cationic Species at Ag Electrodes.- 8.4. Hydrocarbons at Ag Films and Au Electrodes.- 8.5. SERS under Nonstandard Conditions and in Nonaqueous Media.- References.- 7. ESR Spectroscopy of Electrode Processes.- 1. Introduction.- 1.1. External Generation Methods.- 1.2. Internal Generation Methods.- 2. Theory.- 2.1. Introductory Remarks.- 2.2. The g-Value.- 2.3. Hyperfine Splitting.- 2.4. Linewidths.- 2.5. The ESR Spectrometer.- 3. Practice.- 3.1. The Allendoerfer Cell.- 3.2. The Compton-Coles Cell.- 3.3. The Compton-Waller Cell.- 3.4 Some Practical Hints.- 4. Applications.- 4.1. Radical Identification.- 4.2. Spin Trapping.- 4.3. The Kinetics and Mechanisms of Electrode Reactions.- 4.4. Dynamic Processes and ESR Lineshapes.- 4.5. Adsorbed Radicals.- References.- 8. Mossbauer Spectroscopy.- 1. Introduction.- 2. Theoretical Aspects.- 2.1. Recoil Energy, Resonance, and Doppler Effect.- 2.2. Phonons, Mossbauer Effect, and Recoilless Fraction.- 2.3. Electric Hyperfine Interactions.- 2.3.1. Isomer Shift.- 2.3.2. Quadrupole Splitting.- 2.4. Magnetic Hyperfine Interaction.- 3. Experimental Aspects.- 3.1. Instrumentation and Modes of Operation.- 3.2. Sources, Data Acquisition, and Data Analysis.- 3.3. In Situ Mossbauer Spectroscopy.- 3.4. Quasi In Situ Mossbauer Spectroscopy.- 3.4.1. Quasi In Situ Conversion Electron Mossbauer Spectroscopy.- 3.4.2. Low-Temperature Quenching.- 3.5. Limitations of the Technique.- 4. Model Systems.- 4.1. Electrochemical Properties of Iron and Its Oxides.- 4.1.1. The Iron Oxyhydroxide System.- 4.1.2. The Passive Film of Iron.- 4.2. Mixed Ni-Fe Oxyhydroxides as Electrocatalysts for Oxygen Evolution.- 4.3. Prussian Blue.- 4.4. Transition Metal Macrocycles as Catalysts for the Electrochemical Reduction of Dioxygen.- 4.5. Tin.- 4.6. In Situ Emission Mossbauer.- References.
TL;DR: In this paper, the authors used laser scattering on an argon atmospheric pressure microwave plasma jet operating in an air environment to determine profiles of the electron temperature, electron density, gas temperature, partial air pressure and the N2/O2 ratio with a spatial resolution of 50 µm.
Abstract: Laser scattering provides a very direct method for measuring the local densities and temperatures inside a plasma. We present new experimental results of laser scattering on an argon atmospheric pressure microwave plasma jet operating in an air environment. The plasma is very small so a high spatial resolution is required to study the effect of the penetration of air molecules into the plasma. The scattering signal has three overlapping contributions: Rayleigh scattering from heavy particles, Thomson scattering from free electrons and Raman scattering from molecules. The Rayleigh scattering signal is filtered out optically with a triple grating spectrometer. The disentanglement of the Thomson and Raman signals is done with a newly designed fitting method. With a single measurement we determine profiles of the electron temperature, electron density, gas temperature, partial air pressure and the N2/O2 ratio, with a spatial resolution of 50 µm, and including absolute calibration.
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01 Jan 2012
TL;DR: In this chapter the history and a review of the recent progress of Mie scattering and Mie-related light scattering theories and available computational programs is presented and short outlines of the various methods are given.
Abstract: In optical particle characterisation and aerosol science today light scattering simulations are regarded as an indispensable tool to develop new particle characterisation techniques or in solving inverse light scattering problems. Mie scattering and related computational methods have evolved rapidly during the past decade such that scattering computations for spherical scatterers a few order of magnitudes larger, than the incident wavelength can be easily performed. This significant progress has resulted from rapid advances in computational algorithms developed in this field and from improved computer hardware. In this chapter the history and a review of the recent progress of Mie scattering and Mie-related light scattering theories and available computational programs is presented. We will focus on Mie scattering theories but as there is much overlap to related scattering theories they will also be mentioned where appropriate. Short outlines of the various methods are given. This review is of course biased by my interest in optical particle characterisation and my daily reading.
TL;DR: The basic concepts of light scattering measurements are reviewed and four critical aspects of the analysis and interpretation of DLS results are addressed, including how temperature, solvent viscosity, and inter‐particle interactions may also influence particle size determination.
TL;DR: In this paper, the authors determined the impact of HIUS on the thermal aggregation, gelation, foaming and emulsifying properties of egg white (EW) proteins using an ultrasonic processor Vibra Cell Sonics.
TL;DR: An asymmetric flow field flow fractionation (A4F) multidetector system in combination with a method to distinguish and quantify the particle and dissolved Ag fractions (ICPMS after ultracentrifugation) for the characterization of Ag-NP products with different degrees of polydispersities is presented.
Abstract: Due to the already prevalent and increasing use of silver-nanoparticle (Ag-NP) products and the raised concerns in particular for the aquatic environment, analytical techniques for the characterization of such products are of need. However, because Ag-NP products are of different compositions and polydispersities, analysis especially of the size distribution is challenging. In this work, an asymmetric flow field flow fractionation (A4F) multidetector system (UV/vis, light scattering, inductively coupled plasma mass spectrometry - ICPMS), in combination with a method to distinguish and quantify the particle and dissolved Ag fractions (ICPMS after ultracentrifugation), for the characterization of Ag-NP products with different degrees of polydispersities is presented. For validation and to outline benefits and limitations, results obtained from batch dynamic light scattering (batch-DLS) and transmission electron microscopy (TEM) were compared. With the developed method a comprehensive understanding in terms ...
TL;DR: An integration of dynamic light scattering (DLS) and optical coherence tomography (OCT) for high-resolution 3D imaging of heterogeneous diffusion and flow is introduced and a fitting algorithm is developed to estimate dynamic parameters including the axial and transverse velocities and the diffusion coefficient.
Abstract: We introduce an integration of dynamic light scattering (DLS) and optical coherence tomography (OCT) for high-resolution 3D imaging of heterogeneous diffusion and flow. DLS analyzes fluctuations in light scattered by particles to measure diffusion or flow of the particles, and OCT uses coherence gating to collect light only scattered from a small volume for high-resolution structural imaging. Therefore, the integration of DLS and OCT enables high-resolution 3D imaging of diffusion and flow. We derived a theory under the assumption that static and moving particles are mixed within the OCT resolution volume and the moving particles can exhibit either diffusive or translational motion. Based on this theory, we developed a fitting algorithm to estimate dynamic parameters including the axial and transverse velocities and the diffusion coefficient. We validated DLS-OCT measurements of diffusion and flow through numerical simulations and phantom experiments. As an example application, we performed DLS-OCT imaging of the living animal brain, resulting in 3D maps of the absolute and axial velocities, the diffusion coefficient, and the coefficient of determination.
TL;DR: In this paper, the effects of treating TiO2 nanocrystalline films with different concentrations of TiCl4 (5−500 mM) on the film morphology, charge-carrier dynamics, and performance of dye-sensitized solar cells were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopy.
Abstract: We report on the effects of treating TiO2 nanocrystalline films with different concentrations of TiCl4 (5–500 mM) on the film morphology, charge-carrier dynamics, and performance of dye-sensitized solar cells. Transport and recombination in the TiCl4-treated films were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. These studies showed that, at a low TiCl4 concentration (5 mM), the electron diffusion coefficient in the annealed film increased. At intermediate TiCl4 concentrations (15–50 mM), the surface area of the films increased, resulting in an increase of light harvesting and overall power conversion efficiency. At a high TiCl4 concentration (500 mM), light scattering in the film in the long wavelength region of the visible spectrum was enhanced, but the averaged pore size of the film became narrower, resulting in slower transport and loss of cell performance.
TL;DR: The Amsterdam-Granada Light Scattering Database (www.iaa.es/scattering) as discussed by the authors is a light scattering database created by the IAA Cosmic Dust Laboratory (CoDuLab) in Granada, Spain.
Abstract: The Amsterdam Light Scattering Database proved to be a very successful way of promoting the use of the data obtained with the Amsterdam Light Scattering apparatus at optical wavelengths. Many different research groups around the world made use of the experimental data. After the closing down of the Dutch scattering apparatus, a modernized and improved descendant, the IAA Cosmic Dust Laboratory (CoDuLab), has been constructed at the Instituto de Astrofisica de Andalucia (IAA) in Granada, Spain. The first results of this instrument for water droplets and for two samples of clay particles have been published. We would now like to make these data also available to the community in digital form by introducing a new light scattering database, the Amsterdam–Granada Light Scattering Database ( www.iaa.es/scattering ). By combining the data from the two instruments in one database we ensure the continued availability of the old data, and we prevent fragmentation of important data over different databases. In this paper we present the Amsterdam–Granada Light Scattering Database.
TL;DR: Combining quantitative photothermal microscopy and light scattering microscopy as well as accurate MIE scattering calculations on single gold nanoparticles, it is revealed that the mechanism of photothermal single-molecule/particle detection is quantitatively explained by a nanolensing effect.
Abstract: Combining quantitative photothermal microscopy and light scattering microscopy as well as accurate MIE scattering calculations on single gold nanoparticles, we reveal that the mechanism of photothermal single-molecule/particle detection is quantitatively explained by a nanolensing effect. The lensing action is the result of the long-range character of the refractive index profile. It splits the focal detection volume into two regions. Our results lay the foundation for future developments and quantitative applications of single-molecule absorption microscopy.
TL;DR: From the measured transmission spectra, microscopic scattering parameters are determined which allow us to show that quasi-cylindrical waves affect EOT only for high densities, when the hole spacing is roughly one wavelength.
Abstract: Results on light scattering from metal hole arrays show the relative importance of surface plasmon polaritons and quasi-cylindrical waves in extraordinary optical transmission. Over a decade ago, the 'extraordinary optical transmission' effect was discovered, in which a metal film perforated by a regular array of subwavelength holes shows unexpectedly high light transmittance at specific wavelengths. The effect was found, in part, to depend on surface plasmons, stimulating a renewed interest in plasmonics, but more recently so-called quasicylindrical waves have also been implicated. A detailed study by Frerik van Beijnum et al., involving hole arrays in metal films with varying hole density, now provides definitive quantitative evidence for the respective roles of surface plasmons and quasicylindrical waves, bringing a more complete understanding of the extraordinary optical transmission effect and opening up new possible design strategies. A metal film perforated by a regular array of subwavelength holes shows unexpectedly large transmission at particular wavelengths, a phenomenon known as the extraordinary optical transmission (EOT) of metal hole arrays1. EOT was first attributed to surface plasmon polaritons, stimulating a renewed interest in plasmonics2,3,4 and metallic surfaces with subwavelength features5,6,7. Experiments soon revealed that the field diffracted at a hole or slit is not a surface plasmon polariton mode alone8. Further theoretical analysis9 predicted that the extra contribution, from quasi-cylindrical waves10,11,12,13, also affects EOT. Here we report the experimental demonstration of the relative importance of surface plasmon polaritons and quasi-cylindrical waves in EOT by considering hole arrays of different hole densities. From the measured transmission spectra, we determine microscopic scattering parameters which allow us to show that quasi-cylindrical waves affect EOT only for high densities, when the hole spacing is roughly one wavelength. Apart from providing a deeper understanding of EOT, the determination of microscopic scattering parameters from the measurement of macroscopic optical properties paves the way to novel design strategies.
TL;DR: This study developed a facile and real-time method for estimating the diameter of single gold nanoparticles (GNPs) that range from 35 to 110 nm in diameter using the chrominance of the GNP's plasmon resonance scattering light that is captured by a dark-field microscope (DFM).
Abstract: Noble metal nanoparticles have excellent optical and chemical properties and are widely used in optics, sensors, and biomedicines. The inherent characteristics of metal nanoparticles, particularly their size, play important roles in their applications. The ability to readily measure the size of single nanomaterials on-site is crucial to the rapid development of single-particle sensors. In this study, we developed a facile and real-time method for estimating the diameter of single gold nanoparticles (GNPs) that range from 35 to 110 nm in diameter; this technique uses the chrominance of the GNP’s plasmon resonance scattering light that is captured by a dark-field microscope (DFM). The RGB (three primary colors, red, green, and blue) chrominance information from the dark-field image can be directly converted into the diameters of the GNPs using the relationship between the particle size and the scattering light peak wavelength; this conversion was carried out using Matlab program based on an RGB-To-Wavelengt...
TL;DR: In this article, the authors demonstrate the full control of polarization dependent light paths through a highly scattering medium by only shaping the incoming wavefront, which is independent of the incident beam's polarization and has no spatial restrictions.
Abstract: Current non-invasive imaging and manipulation of biological systems heavily rely on using light as the probing tool. However, light propagation through highly turbid media such as biological tissue undergo multiple light scattering which results in significant scrambling of light paths and polarization information. Here we demonstrate the full control of polarization dependent light paths through a highly scattering medium by only shaping the incoming wavefront. The resulting polarized state is independent of the incident beam’s polarization and has no spatial restrictions. We also show that a turbid medium can be used as a dynamic wave plate by controlling the phase of combined orthogonal polarization states. This approach may find direct applications in efficient energy transfer for photothermal therapy and the transfer of angular momentum in optical manipulation of biological systems.
TL;DR: A non-trivial link between these two phenomena is revealed, through the Fano interference between Bragg scattering and disorder-induced scattering, that triggers both localization and de-localization in random systems.
Abstract: Light localization in disordered systems and Bragg scattering in regular periodic structures are considered traditionally as two entirely opposite phenomena: disorder leads to degradation of coherent Bragg scattering whereas Anderson localization is suppressed by periodicity. Here we reveal a non-trivial link between these two phenomena, through the Fano interference between Bragg scattering and disorder-induced scattering, that triggers both localization and de-localization in random systems. We find unexpected transmission enhancement and spectrum inversion when the Bragg stop-bands are transformed into the Bragg pass-bands solely owing to disorder. Fano resonances are always associated with coherent scattering in regular systems, but our discovery of disorder-induced Fano resonances may provide novel insights into many features of the transport phenomena of photons, phonons, and electrons. Owning to ergodicity, the Fano resonance is a fingerprint feature for any realization of the structure with a certain degree of disorder.
TL;DR: An experimental study of the dynamical arrest transition for a model system consisting of octadecyl coated silica suspended in n-tetradecane from dilute to concentrated conditions spanning the state diagram, suggesting dynamical Arrest is sensitive to the physical mechanism of attraction.
Abstract: We report an experimental study of the dynamical arrest transition for a model system consisting of octadecyl coated silica suspended in n-tetradecane from dilute to concentrated conditions spanning the state diagram. The dispersion’s interparticle potential is tuned by temperature affecting the brush conformation leading to a thermoreversible model system. The critical temperature for dynamical arrest, T*, is determined as a function of dispersion volume fraction by small-amplitude dynamic oscillatory shear rheology. We corroborate this transition temperature by measuring a power-law decay of the autocorrelation function and a loss of ergodicity via fiber-optic quasi-elastic light scattering. The structure at T* is measured using small-angle neutron scattering. The scattering intensity is fit to extract the interparticle pair-potential using the Ornstein–Zernike equation with the Percus–Yevick closure approximation, assuming a square-well interaction potential with a short-range interaction (1% of partic...
TL;DR: The results from the simulated radial distribution functions and light scattering experiments indicate that variation in the structure of side chains and polarity of functional groups leads to significant variations in molecular association, dynamics of molecular nanoaggregation and structure of nanoaggregates.
Abstract: Four synthetic perylene bisimide-based polyaromatic (PA) surfactants with a structural or functional group difference in their attached hydrophilic/hydrophobic substituent side chains were used to probe structure–nanoaggregation relations in organic media by molecular dynamics simulations and dynamic light scattering. The results from the simulated radial distribution functions and light scattering experiments indicate that variation in the structure of side chains and polarity of functional groups leads to significant variations in molecular association, dynamics of molecular nanoaggregation and structure of nanoaggregates. The aggregates of PA surfactant molecules grow to much larger sizes in heptane than in toluene. The aromatic solvent is shown to hinder molecular association by weakening π–π stacking, demonstrating the control of molecular aggregation by tuning solvent properties. In aliphatic solvent, the aggregates formed from PA surfactants of aliphatic alkyl groups and phenylalanine derivatives a...
TL;DR: In this paper, a model based on optical phonon scattering is developed to explain peculiarities in the current drive, transconductance, and high-speed behavior of short-gate-length GaN transistors.
Abstract: A model based on optical phonon scattering is developed to explain peculiarities in the current drive, transconductance, and high-speed behavior of short-gate-length GaN transistors. The model is able to resolve these peculiarities and provides a simple way to explain transistor behavior in any semiconductor material system in which electron-optical-phonon scattering is strong.