Refractive Indices of Mixtures

In general, for calamitic liquid crystals f f is satisfied so that, according to Eq. (10), not only is greater than but also the dispersion of is greater than 

On the basis of Vuks formula (Eq. 8), Wu [72] derived a simple dispersion equation for the birefringence  

In accordance with the experimental results [17, 51] the birefringence in the IR region is expected to be nearly independent of the wavelength and mainly determined by the electronic transition moment. The contribution of the molecular vibrational bands to the birefringence is limited to the vicinity of these resonance bands. In the IR region, positive and negative dispersion is observed. When the absorption of the extraordinary ray is more pronounced than that of the ordinary ray the dispersion is positive, and vice versa [17, 51]. 

A more detailed analysis of the dispersion of and An has been made [70, 73]. Whereby not only the long-wave electronic band but also two further bands are involved in the dispersion equation. Besides a cr— CT transition in the vacuum UV region (at lq) two 7t n transitions at longer wavelengths A and A2 (UV or visible) are considered. In this way more exact 

The contributions of the three bands (i. e. of the (T and k electrons) have been calculated quantitatively. It was found that the longest wavelength band (A2) makes the primary contribution to the birefringence because this band has the largest absorption anisotropy. However, the n electrons make a smaller contribution to the absolute values of the refractive indices n and n [70, 73]. 

---

TobJe Et6 - Refractive Indices of Mixtures of Ethyleneglycol Dinitrate and Nitroglycerin... 

In general the refractive indices of mixtures of non-interacting components plot smoothly against the proportions present the same is true of specific or molecular refractions. Equations (3) and (4)—when Ri and i 2, or r1 and r2, are known—obviously make possible the estimation of a concentration w2 or f2 by measurement of n12 and dl2 (since... 

Fig. 8 Refractive indices of mixtures of genapol 070 and octanol in (a). Refractive indices of mixtures of water with different cosolvents (b)...

We had occasion to extend the concept to the development of materials for potential use in intraocular lenses [45]. Appropriately shaped dry resin lenses were to be surgically implanted. Upon exposure to the fluids in the eye, the polymer was to swell and assume the correct optical shape for proper vision. This concept required that the polymer should take up at least 409/o of its weight as water to produce a swollen polymer that had a refractive index of no less that 1,40 to permit the proper optical corrections to be applied to the lens. Assuming that refractive indices of mixtures or solutions are additive, this requires a polymer with a refractive index about 1.5 so that 40 70 of water with nn 1.33 will result in a hydrogel in the desired... 

Special care has to be taken if the polymer is only soluble in a solvent mixture or if a certain property, e.g., a definite value of the second virial coefficient, needs to be adjusted by adding another solvent. In this case the analysis is complicated due to the different refractive indices of the solvent components [32]. In case of a binary solvent mixture we find, that formally Equation (42) is still valid. The refractive index increment needs to be replaced by an increment accounting for a complex formation of the polymer and the solvent mixture, when one of the solvents adsorbs preferentially on the polymer. Instead of measuring the true molar mass Mw the apparent molar mass Mapp is measured. How large the difference is depends on the difference between the refractive index increments ([dn/dc) — (dn/dc)A>0. (dn/dc)fl is the increment determined in the mixed solvents in osmotic equilibrium, while (dn/dc)A0 is determined for infinite dilution of the polymer in solvent A. For clarity we omitted the fixed parameters such as temperature, T, and pressure, p. 

The relative adsorptions of the two liquids (CCI4 and CyH g) was found by measuring refractive indices of the initial and final mixtures after contact with the higher area silica. They are found to be almost identical and apparent adsorptions (Table II) are low. 

It has also been possible, in various ways which cannot be detailed here, to prepare both the keto- and enol-forms of ethyl acetoacetate in the pure state (Knorr, K. H. Meyer). Their physical constants are altogether different. The refractive index, for example, is 1-4225 (D10 ) for the keto-form and 1-4480 for the enol-form. From determinations of the refractive indices of equilibrium mixtures the content of both forms can be calculated by interpolation (Knorr, 1911), and these results have been confirmed spectroscopically (Hantzsch, 1910). 

Al-Kandary, J., Al-Jimaz, A.S., and Abdul-Latif, A.-H.M. Densities, viscosities, and refractive indices of binary mixtures of anisole with benzene, methylbenzene, ethylbenzene, propylbenzene, and butylbenzene at (293.15 and 303.15) K, /. Chem. Eng. Data, 51(1) 99-103, 2006. 

Moumouzias, G. and Ritzoulis, G. Relative permittivities and refractive indices of propylene carbonate + toluene mixtures from 283.15 K to 313.15 K, J. Chem. Eng. Data, 42(4) 710-713, 1997. 

Resa, J.M., Gonzalez, C., de Eandaluce, S.O., and Eanz, J. Densities, excess molar volumes, and refractive indices of ethyl acetate and aromatic hydrocarbon binary mixtures. J. Chem. Thermodyn, 34(7) 995-1004. 2002. 

As the difference between refractive indices of NG and EGDN is fairly large, Rinkenbach decided to apply this difference to analysis of EGDN—NG mixtures. He used a precision Leitz xeftactometer, equipped with a water jacket and calibrated thermometer. Indices were derd over a wide range of temps for each substance previously... 

Inspection shows that the refractive indices of nitrates of the glycols are practically identical and much lower than those of Nitroglycerin and the Nitroglycerin-Nitro-polyglycerin mixture. Determination of the refractive index of a sample should give at least a qualitative indication of the presence of the glycol compounds... 

Fig. 1 Accessories for diffuse reflectance spectroscopy (A) Integrating sphere with hemispherical radiation collection (B) Accessory based on ellipsoidal mirrors, used within the sample compartment of the spectrometer (C) Rotational ellipsoidal mirror device with dedicated detector and (D) Bifurcated fiber optic-based accessory (also shown is the random mixture of fibers for illumination and detection compared with devices based on reflection optics the acceptance cone for radiation delivery and collection is limited and depends on the refractive indices of the core and cladding material).

Fig. 3.1. Photograph of five sols of colloidal 1.336, 1.407, 1.481, 1.525 and 1.583 (+0.004) gold prepared in water and in mixtures of butyl respectively. (Reprinted with permission from acetate and CS2. Refractive indices of the [64], 1994, American Chemical Society),...

Figure 8. Refractive indices of various volumes of 20/80 ethanol/ Indolene mixture before exposure (—) and after exposure (----------------) to nitrile rubber.

Figure 9. Refractive indices of 25/75 methanol/Indolene mixture before and after exposure to acrylate rubber for various time periods.

---