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Light scattering specific intensity

Some specific properties of macromolecules are employed for the detection in polymer HPLC. It is primarily the large size of detected species, which is comparable with the wavelength of the visible light. As a result, the light beam interacting with the macromolecules is intensively scattered [272]. The extent of light scattering under otherwise constant experimental conditions depends on the molar mass of macromolecules. [Pg.493]

Critical phenomena of gels have been studied mainly by dynamic light scattering technique, which is one of the most well-established methods to study these phenomena [18-20]. Recently, the critical phenomena of gels were also studied by friction measurement [85, 86] and by calorimetry [55, 56]. In the case of these methods, the divergence of the specific heat or dissipation of the friction coefficient could be monitored as a function of an external intensive variable, such as temperature. These phenomena might be more plausible to some readers than the divergence of the scattered intensity since they can observe the critical phenomena in terms of a macroscopic physical parameter. [Pg.32]

The influence of homogeneity of structure of gels on the phase transitions was studied by us for the networks of copolymers of methacrylamide with SMA in the mixtures of water with isopropanol [17]. The specific feature of these gels is the microinhomogeneity of their structure, which is manifested in intensive light scattering. For this type of system, it would be natural to expect an absence of... [Pg.149]

All factors related to the arrangement of the polymer chain in space are classified as tertiary structure. Parameters measurable directly (the radius of gyration RG, the end-to end distance h, the hydrodynamical radius RH, and the asymmetry in light scattering intensity) or indirectly (interaction parameters, the second virial coefficient A2) are related to the dimensions, such as size and shape of the polymer chain in a specific solvent under given conditions of temperature and pressure. For the exact determination of the coil size of macromolecules, it is necessary to ensure that measure-... [Pg.131]

Dynamic processes at thermodynamic equilibrium that occur within a time range from sub-microseconds to seconds can be probed without the imposition of a transient disturbance by optical intensity fluctuation spectroscopy. As such, dynamic light scattering (DLS) [155] measures the fluctuation of quasielastic scattering intensity and fluorescence correlation spectroscopy (FCS) [156-158] measures concentration fluctuations of specific fluorescent molecules... [Pg.136]

At a specific radial distance the moving particles interrupt and attenuate a light beam, the intensity of which is measured by a photodetector. The particle size is related to the appearance time at the photodetector by means of Stokes Law for centrifugation. The concentration of particles is obtained from the photodetector response and the application of Mie scattering theory.(1) A very Important step in this operation is the formation of a density gradient within the spin fluid to allow a hydrodynamically stable separation of the suspended particles. An accepted method for forming this spin fluid density gradient within the disc cavity is the widely used and patented (2) Joyce-Loebl Buffered Line Start... [Pg.191]

The specific intensity is an important quantity because it depends mainly on sample D) and laser (Pd) variables and not on spectrometer parameters such as collection angle, quantum efficiently, and the like L indicates what the spectrometer has to work with while collecting and detecting scattered light. If we consider the example of a clear sample and 180° backscattered geometry with = 0.1 cm (as in Fig. 2.5), then L can be calculated for a variety of samples. Table 2.4 lists several specific intensities for samples of... [Pg.33]

Operationally, the optical components used in turbidimeters and nephelometers are similar to those used in fluorometers or photometers. For example, the light sources commonly used are quartz halogen lamps, xenon lamps, and lasers. He-Ne lasers, which operate at 633 nm, have typically been used for light-scattering applications, such as nephelometric immunoassays and particle size and shape determinations. The laser beam is used specifically in some nephelometers because of its high intensity in addition, the coherent nature of laser light makes it ideally suited for nephelometric applications. [Pg.88]


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