Measurements scattering

In these t is the turbidity ixo, the refractive index of the solvent n, the refractive index of the solution X, the wave length of the light used n, the number of particles per cubic centimeter N, Avogadro s number M, the molecular weight c, the concentration in grams per cubic centimeter and 

A similar equation (17), obtained by Doty, Zimm and Mark, relates the turbidity (actually, the extinction coefficient in cm. due to concentration fluctuations, which is the principal cause of heterogeneity) to the refractive index, n the concentration, c the refractive index increment dn/dc)] and the molecular weight, M, of the solute. 

In equation 17, X represents the wave length of the monochromatic light used, A o is Avogadro s number, and B, which measures the deviation from van t Hoff s law, is the coefficient of the last term (c ) in the expres- 

Although the method has considerable merit, the greatest difficulty in its use arises from the large discrepancies caused by the presence of small amounts of impurities. Even in the work thus far reported, there is no proof that the dispersions were optically clean. 

X-rays are the most common type of radiation used to analyze polymers. We also employ visible light and neutron beams for specialized analytical purposes. We use small-angle laser 

Collimated Single Scattered beam crystal radiation 

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The goal of URT is to obtain reflectivity images from back-scattered measurements. This consists in a Fourier synthesis problem, and the first task is to correctly cover the frequency space of the "object" r. Let for simplicity the dimension of the physical space be 2. 

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

Phospholipid molecules form bilayer films or membranes about 5 nm in thickness as illustrated in Fig. XV-10. Vesicles or liposomes are closed bilayer shells in the 100-1000-nm size range formed on sonication of bilayer forming amphiphiles. Vesicles find use as controlled release and delivery vehicles in cosmetic lotions, agrochemicals, and, potentially, drugs. The advances in cryoelec-tron microscopy (see Section VIII-2A) in recent years have aided their characterization [70-72]. Additional light and x-ray scattering measurements reveal bilayer thickness and phase transitions [70, 71]. Differential thermal analysis... 

Miscible blends of high molecular weight polymers often exhibit LOST behavior (3) blends that are miscible only because of relatively low molecular weights may show UCST behavior (11). The cloud-point temperatures associated with Hquid—Hquid phase separation can often be adequately determined by simple visual observations (39) nevertheless, instmmented light transmission or scattering measurements frequendy are used (49). The cloud point observed maybe a sensitive function of the rate of temperature change used, owing to the kinetics of the phase-separation process (39). 

Light-scattering measurements made over two suitably chosen angle intervals can combine with depolarized light-scattering measurements to... 

C. Incoherent Neutron Scattering Measurements of Lipid Dynamics... 

A schematic of a PL system layout is shown in Figure 5. This optical system is very similar to that required for absorption, reflectance, modulated reflectance, and Raman scattering measurements. Many custom systems are designed to perform several of these techniques, simultaneously or with only small modifications. 

J. C. Stover. Optical Scattering Measurement and Analysis. McGraw-Hill,... 

Holden et al. [27] reported the first Raman results on nanotubes produced from a Co-catalyzed carbon arc. Thread-like material removed from the chamber was encapsulated in a Pyrex ampoule in -500 Torr of He gas for Raman scattering measurements. Sharp first-order lines were observed at 1566 and 1592 cm and second-order lines al 2681 and 3180 cm , but only when cobalt was present in the core of the anode. These sharp lines had not been observed previously in... 

Witkowski, W.R., Miller, S.M. and Rawlings, J.B., 1990. Light scattering measurements to estimate kinetic parameters of crystallization. In Crystallization as a separation process, ACS Symposium Series, 438, 102. 

Polyetherimides show no crystallinity as evidenced from calorimetry measurements. The heteroarylene like phenylquinoxaline [27], oxadiazole [30], and benzoxa-zole [56] activated polyethers show TgS from DSC thermograms, with no evidence of crystallization, indicating amorphous or glassy morphology. Furthermore, wide angle x-ray scattering measurements show no evidence of crystalline or liquid crystalline type morphologies, consistent with an amorphous structure. F polyether... 

Fig. 1-11. Fate of an x-ray beam. Two types of events occur as an x-ray beam is absorbed in matter—more precisely, as x-ray quanta disappear from the beam. These types of events are photoelectric absorption, measured by r, and scattering, measured by a. (See Eq. 1-8.)...

Figure 5B. Correlation of right-angle light scatter measured by fluorometry and flow cytometry. The top panel shows flow-cytometric data of side scatter of fixed, stained cells during the time course of stimulation by 1-nM (solid line, solid circles) or 0.01-nH (dashed line, open circle) FLPEP. The bottom panel shows the corresponding right-angle light-scatter data acquired pseudo-simultaneously on live cells in the fluorometer. The flow-cytometric data have been averaged, but the fluorometry data are plotted for both duplicates from one donor. Reproduced with permission from Ref. 27. Copyright 1985 Rockefeller University Press.

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