Laser refractometry

The method takes advantage of the steric hindrance of the polystyryllithium living end, which in combination with the excess silane used for the linking reaction, reduces the possibility for the formation of the coupled byproduct. The reaction sequence was monitored by SEC and the reaction products were characterized by MO, differential laser refractometry and LALLS, revealing that well defined polymers were prepared. 

Optical interferometry has an interest in its own right in the determination of the refractive indices of gases. For example, precise laser refractometry of pure helium gas can lead to a better determination of the Boltzmann constant [80] when combined with the latest ab initio theory of atomic polarisability [81]. 

Syunyaev, 2008). Concentration oscillations in water solutions of dye were also observed by laser refractometry. It is possible to suppose that adsorption is kinetically limited by diffusion. The mechanism of diffusion relaxation suggested by I. Akhatov is realized (Akhatov, 1988, as cited in Syunyaev at al., 2009). The classic Pick s law can be generalized by introduction of additional relaxation item... 

As indicated, the specific refractive index increment is best measured by differential refractometry or interferometry. Experimental procedures as well as tabulated values of dn/ dc for many systems have been presented elsewhere40,63K The relevant wavelength and temperature are those used for LS. The value of X0 is invariably 436 or 546 nm, but with the advent of laser LS, values of dn/dc at other wavelengths are required. These can be estimated with good reliability using a Cauchy type of dispersion (dn/dc a 1/Xq). For example the values of dn dc for aqueous solutions of the bacterium T-ferrioxidans at 18 °C are 0.159, 0.141 and 0.125 ml/gm at X0 = 488, 633 and 1060 nm respectively64 ... 

Differential Refractometry (dn/dc). Stock solutions of polymer were prepared with known concentrations (w/v) in the solvent of choice, and the specific refractive index increment (dn/dc) was measured at 26 deg C with a KMX-16 Laser Differential Refractometer (LDC/Milton Roy). Sample concentrations typically were ca. 5 x 10 3 gm/ml. 

The samples prepared by this chlorosilane route are characterized by high degrees of molecular and compositional homogeneities, as was confirmed by the exhaustive characterization data provided by SEC, membrane osmometry, low angle laser light scattering, differential refractometry, vapor pressure osmometry, UV-SEC, and NMR. The most important feature of the method is that every step of the reaction is monitored by taking small aliquots from the reaction mixture. 

Roth, N., Anders, K. and Frohn, A. Size insensitive rainbow refractometry Theoretical aspects. Proc. 8th Int. Symp. on Appl. of Laser Techniques to Fluid Mechanics, Lisbon, Paper 9.2 (1996)... 

Refractometry is another approach for direct detection of carbohydrates. An interesting holography-based refractive index detector was implemented by Burggraf et al. [207]. A cyclic channel of 80 mm in circumference and 10-p.m deep was fabricated. The detection scheme was constructed having a diode laser beam (670 nm) split into two beams, one passing through the separation... 

Table 1 shows the refractive indices for several materials. The variation of refractive index as a function of electromagnetic radiation wavelength (dispersion spectrum) provides simultaneous information about the polarizibility and absorption properties of the sample. The rapid development of modern optical and imaging technologies such as lasers and photodiode arrays creates opportunities for application of refractometry to small analytical systems and multidimensional monitoring. 

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