Light scattering

About: Light scattering is a research topic. Over the lifetime, 37721 publications have been published within this topic receiving 861581 citations.

Self-Consistent Results for a GaAs/Al x Ga 1-x As Heterojunction. I. Subband Structure and Light-Scattering Spectra

Abstract: The subband structure of a two-dimensional electron system at a GaAs/Al x Ga 1- x As heterojunction interface is calculated. Many-body exchange and correlation effects are taken into account in the local density-functional approximation. They are shown to be unimportant but not negligibly small. Spectra of light scatterings are also calculated. Results are in reasonable agreement with existing experiments.

Light Scattering, Size Exclusion Chromatography and Asymmetric Flow Field Flow Fractionation: Powerful Tools for the Characterization of Polymers, Proteins and Nanoparticles

Abstract: Preface. 1 Polymers. 1.1 Introduction. 1.2 Molecular Structure of Polymers. 1.2.1 Macromolecules in Dilute Solution. 1.3 Molar Mass Distribution. 1.3.1 Description of Molar Mass Distribution. 1.3.1.1 Distribution Functions. 1.3.1.2 Molar Mass Averages. 1.4 Methods for the Determination of Molar Mass. 1.4.1 Method of End Groups. 1.4.2 Osmometry. 1.4.2.1 Vapor Pressure Osmometry. 1.4.2.2 Membrane osmometry. 1.4.3 Dilute Solution Viscometry. 1.4.3.1 Properties of Mark-Houwink Exponent. 1.4.3.2 Molecular Size from Intrinsic Viscosity. 1.4.3.3 Dependence of Intrinsic Viscosity on Polymer Structure, Temperature and Solvent. 1.4.4 Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry. 1.4.5 Analytical Ultracentrifugation. 1.5 Keynotes. 1.6 References. 2 Light Scattering. 2.1 Theory and Basic Principles. 2.2 Types of Light Scattering. 2.2.1 Static Light Scattering. 2.2.1.1 Particle Scattering Functions. 2.2.1.2 Light Scattering Formalisms. 2.2.1.3 Processing the Experimental Data. 2.2.2 Dynamic Light Scattering. 2.3 Light Scattering Instrumentation. 2.4 Specific Refractive Index Increment. 2.5 Light Scattering in Batch and Chromatography Mode. 2.6 Parameters Affecting Accuracy of Molar Mass Determined by Light Scattering. 2.7 Examples of Light Scattering Measurement in Batch Mode. 2.8 Keynotes. 2.9 References. 3 Size Exclusion Chromatography. 3.1 Introduction. 3.2 Separation Mechanisms. 3.2.1 Steric Exclusion. 3.2.2 Restricted Diffusion. 3.2.3 Separation by Flow. 3.2.4 Peak Broadening and Separation Efficiency. 3.2.5 Secondary Separation Mechanisms. 3.3 Instrumentation. 3.3.1 Solvents. 3.3.2 Columns and Column Packing. 3.3.3 Detectors. 3.3.3.1 UV Detector. 3.3.3.2 Refractive Index Detector. 3.3.3.3 Infrared Detector. 3.3.3.4 Evaporative Light Scattering Detector. 3.3.3.5 Viscosity Detector. 3.3.3.6 Light Scattering Detector. 3.3.3.7 Other Types of Detectors. 3.4 Column Calibration. 3.4.1 Universal Calibration. 3.4.2 Flow Marker. 3.5 SEC Measurements and Data Processing. 3.5.1 Sample Preparation. 3.5.1.1 Sample Derivatization. 3.5.2 Determination of Molar Mass and Molar Mass Distribution. 3.5.3 Reporting Results. 3.5.4 Characterization of Chemical Composition of Copolymers and Polymer Blends. 3.5.5 Characterization of Oligomers. 3.5.6 Influence of Separation Conditions. 3.5.7 Accuracy, Repeatability and Reproducibility of SEC Measurements. 3.6 Applications of SEC. 3.7 Keynotes. 3.8 References. 4 Combination of SEC and Light Scattering. 4.1 Introduction. 4.2 Data Collection and Processing. 4.2.1 Processing MALS Data. 4.2.1.1 Debye Fit Method. 4.2.1.2 Zimm Fit Method. 4.2.1.3 Berry fit Method. 4.2.1.4 Random Coil Fit Method. 4.2.1.5 Influence of Light Scattering Formalism on Molar Mass and RMS Radius. 4.2.2 Determination of Molar Mass and RMS Radius Averages and Distributions. 4.2.3 Chromatogram Processing. 4.2.4 Influence of Concentration and Second Virial Coefficient. 4.2.5 Repeatability and Reproducibility. 4.2.6 Accuracy of Results. 4.3 Applications of SEC-MALS. 4.3.1 Determination of Molar Mass Distribution. 4.3.2 Fast Determination of Molar Mass. 4.3.3 Characterization of Complex Polymers. 4.3.3.1 Branched Polymers. 4.3.3.2 Copolymers and Polymer Blends. 4.3.4 Conformation Plots. 4.3.5 Mark-Houwink Plots. 4.4 Keynotes. 4.5 References. 5 Asymmetric Flow Field Flow Fractionation. 5.1 Introduction. 5.2 Theory and Basic Principles. 5.2.1 Separation Mechanisms. 5.2.2 Resolution and Band Broadening. 5.3 Instrumentation. 5.4 Measurements and Data Processing. 5.4.1 Influence of Separation Conditions. 5.4.1.1 Isocratic and Gradient Experiments. 5.4.1.2 Overloading. 5.4.2 Practical Measurements. 5.5 A4F Applications. 5.6 Keynotes. 5.7 References. 6 Characterization of Branched Polymers. 6.1 Introduction. 6.2 Detection and Characterization of Branching. 6.2.1 SEC Elution Behavior of Branched Polymers. 6.2.2 Distribution of Branching. 6.2.3 Average Branching Ratios. 6.2.4 Other Methods for the Identification and Characterization of Branching. 6.3 Examples of Characterization of Branching. 6.4 Keynotes. 6.5 References. Symbols. Abbreviations. Index.

Dynamics of Frenkel excitons in disordered molecular aggregates

Abstract: This article reports on the optical dynamics in aggregates of pseudoisocyanine‐bromide and iodide. For PIC‐Br in an ethylene glycol/water glass, the results of resonance light scattering (RLS), time‐resolved emission, and photon echo decay measurements are discussed. Band structure calculations based on a linear‐chain model for the J aggregate have also been performed. The results show that the J band can be described as a disordered Frenkel exciton band in which superradiant states exist that extend over about 100 molecules. Numerical simulation studies of the J band, based on Anderson’s Hamiltonian with uncorrelated diagonal site energies, show that the ratio κ of the disorder parameter D over the nearest‐neighbor coupling parameter J12 is about 0.11. Using the frequency dependence of the ratio between the yields of vibrational fluorescence and Raman scattering as a probe, the dephasing process and derived parameters for the bath correlation function at three different temperatures have also been examin...

Glasses in hard spheres with short-range attraction.

Abstract: We report a detailed experimental study of the structure and dynamics of glassy states in hard spheres with short-range attraction. The system is a suspension of nearly hard-sphere colloidal particles and nonadsorbing linear polymer which induces a depletion attraction between the particles. Observation of crystallization reveals a reentrant glass transition. Static light scattering shows a continuous change in the static structure factors upon increasing attraction. Dynamic light scattering results, which cover 11 orders of magnitude in time, are consistent with the existence of two distinct kinds of glasses, those dominated by interparticle repulsion and caging, and those dominated by attraction. Samples close to the $``{A}_{3}$ point'' predicted by mode coupling theory for such systems show very slow, logarithmic dynamics.

Spectroelectrochemistry: Theory And Practice

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.