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Static Light Scattering
Static light scattering is a technique in physical chemistry that measures the intensity of the scattered light to obtain the average molecular weight ''Mw'' of a macromolecule like a polymer or a protein in solution. Measurement of the scattering intensity at many angles allows calculation of the root mean square radius, also called the radius of gyration ''Rg''. By measuring the scattering intensity for many samples of various concentrations, the second virial coefficient, ''A2'', can be calculated. Static light scattering is also commonly utilized to determine the size of particle suspensions in the sub-μm and supra-μm ranges, via the Lorenz-Mie (see Mie scattering) and Fraunhofer diffraction formalisms, respectively. For static light scattering experiments, a high-intensity monochromatic light, usually a laser, is launched into a solution containing the macromolecules. One or many detectors are used to measure the scattering intensity at one or many angles. The angular depend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
André Guinier
André Guinier (1 August, 1911 – 3 July, 2000) was a French physicist and crystallographer who did pioneering work in the field of X-ray diffraction and solid-state physics. He was credited for the discovery and developments of small-angle X-ray scattering (SAXS) into an indispensable tool for materials science and crystallography. Education and career Guinier was born in Nancy, France, his father Philibert Guinier was a botanist and director of the Nancy branch of the French National School of Forestry. Guinier studied at Lycée Henri-Poincaré before entering the École Normale Supérieure (ENS), where he studied physics from 1930 to 1934. After graduation, he worked as an agrégé-preparateur in the physics laboratory of ENS. In 1939, Guinier discovered SAXS and received his doctorate with a thesis on X-ray crystallography under Charles Mauguin. He then worked at the Conservatoire National des Arts et Métiers, where he became deputy director of the test laboratory in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Chemistry
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids). Some of the relationships that physical chemistry strives to understand include the effects of: # Intermolecular forces that act upon the physical properties of materials ( plasticity, tensile strength, surface tension in liquids). # Reaction kinetics on the rate of a reaction. # The identity of ions and the electrical conductivity of materials. # Surface science and electrochemistry of cell m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Zimm
Partial may refer to: Mathematics *Partial derivative, derivative with respect to one of several variables of a function, with the other variables held constant ** ∂, a symbol that can denote a partial derivative, sometimes pronounced "partial dee" **Partial differential equation, a differential equation that contains unknown multivariable functions and their partial derivatives Other uses *Partial application, in computer science the process of fixing a number of arguments to a function, producing another function *Partial charge or net atomic charge, in chemistry a charge value that is not an integer or whole number *Partial fingerprint, impression of human fingers used in criminology or forensic science *Partial seizure or focal seizure, a seizure that initially affects only one hemisphere of the brain * Partial or Part score, in contract bridge a trick score less than 100, as well as other meanings * Partial or Partial wave, one sound wave of which a complex tone is composed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scattering
In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called ''diffuse reflections'' and unscattered reflections are called ''specular'' (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as far as Isaac Newton in the 17th century). As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" (not then recognized as electromagnetic in nature) in 1800. John Tyndall, a pioneer in light scattering research, noted the connecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Scattering
In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called '' diffuse reflections'' and unscattered reflections are called '' specular'' (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as far as Isaac Newton in the 17th century). As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" (not then recognized as electromagnetic in nature) in 1800. John Tyndall, a pioneer in light scattering research, noted the con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Particle Extinction And Scattering
Single Particle Extinction and Scattering (SPES) is a technique in physics that is used to characterise micro and nanoparticles suspended in a fluid through two independent parameters, the diameter and the effective refractive index. A laser generates a gaussian beam In optics, a Gaussian beam is an idealized beam of electromagnetic radiation whose amplitude envelope in the transverse plane is given by a Gaussian function; this also implies a Gaussian intensity (irradiance) profile. This fundamental (or ... which focuses inside a flow cell. A particle that passes through the focal region generates an interference in the beam, which is collected with a sensor. Through this signal it is possible to derive the real part and the imaginary part of the forward scattering field from each particle. The technique was developed to measure aerosols in air and particles in liquid. References Experimental physics Laser science {{Physics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Light Scattering
Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution. In the scope of DLS, temporal fluctuations are usually analyzed using the intensity or photon autocorrelation function (also known as photon correlation spectroscopy – PCS or quasi-elastic light scattering – QELS). In the time domain analysis, the autocorrelation function (ACF) usually decays starting from zero delay time, and faster dynamics due to smaller particles lead to faster decorrelation of scattered intensity trace. It has been shown that the intensity ACF is the Fourier transform of the power spectrum, and therefore the DLS measurements can be equally well performed in the spectral domain. DLS can also be used to probe the behavior of complex fluids such as concentrated polymer solutions. Setup A monochromatic light source, usually a laser, is shot through a polarizer and into a sample. The s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Static Light Scatter
Differential static light scatter (DSLS) is a term coined to represent the change in total light scatter of a system over time or temperature in a static environment. Static light scattering or SLS and its many types are well outlined in literature and is the base principal for DSLS but varies specifically in that the difference (before and after) is the focus of this measurement. Typically the system will commence measurement at T0 and over the course of time measure the change in light scatter. One of the more practical applications of DSLS is in the area of proteomic research and protein based chemistry. Solution conditions can be varied across samples of a specific protein in a screening scenario and the system can be kept at either a static temperature or be ramped up, or in some cases down. The change will be observed over time and the focus of the calculation is on the amount of change in signal from T0 to Tfinal . This method of analysis provides researchers with data tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrophoretic Light Scattering
Electrophoretic light scattering (also known as laser Doppler electrophoresis and phase analysis light scattering ) is based on dynamic light scattering. The frequency shift or phase shift of an incident laser beam depends on the dispersed particles mobility. With ''dynamic light scattering'', Brownian motion causes particle motion. With ''electrophoretic'' light scattering, oscillating electric field performs this function. The method is used for measuring electrophoretic mobility, from which zeta potential can then be calculated. Instruments for applying the method are commercially available from several manufacturers. The last set of calculations requires information on viscosity and dielectric permittivity of the dispersion medium; appropriate electrophoresis theory is also required. Sample dilution is often necessary to eliminate multiple scattering of the incident laser beam and/or particle interactions. Instrumentation A laser beam passes through the electrophoresis cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Size-exclusion Chromatography
Size-exclusion chromatography, also known as molecular sieve chromatography, is a chromatography, chromatographic method in which molecules in Solution (chemistry), solution are separated by their Chemical structure, shape, and in some cases molecular weight, size. It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers. Typically, when an aqueous solution is used to transport the sample through the column, the technique is known as gel filtration chromatography, versus the name gel permeation chromatography, which is used when an organic solvent is used as a mobile phase. The chromatography column is packed with fine, porous beads which are commonly composed of dextran, agarose, or polyacrylamide polymers. The pore sizes of these beads are used to estimate the dimensions of Macromolecule, macromolecules. SEC is a widely used polymer characterization method because of its ability to provide good molar mass distribution (Mw) resul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
