Subject refractive index

In 1899 Thoms isolated an alcohol from Peru balsam oil, which he termed peruviol. This body was stated to have powerful antiseptic properties, but has not been further investigated until Schimmel Co. took up the subject. The oil after saponification was fractionated, and after benzyl alcohol had distilled over, a light oil with characteristic balsamic odour passed over. It boiled at 125° to 127° at 4 mm., and had a specific gravity 0 8987, optical rotation -1- 12° 22, and refractive index 1-48982. This body appeared to be identical with Hesse s nerolidol, whilst in physical and chemical properties it closely resembles peruviol. The characters of the various preparations were as follows —... 

Once initiated, and provided the surface continues to be exposed to the environment, the process of hydration continues at a slow, but measurable rate. The adsorption of the water is accompanied by changes in the physical properties of the obsidian. The refractive index of the obsidian, for example, is altered as it becomes hydrated. If the obsidian was subjected to alternative wet and dry periods, successive hydrated layers are formed on the surface. The differences in refractive index between the bulk and the hydrated layer (or layers) creates an interface between the bulk and the hydrated layer, and between the layers, that stands out sharply when observing a cross-cut section of obsidian under a microscope (see Fig. 23). Thus the thickness of the hydrated layer, or layers, can be measured. 

Separated components emerging in the column effluent can be monitored by means of a physical measurement, e.g. UV or visible absorbance, refractive index, conductivity or radioactivity. Alternatively, separate fractions can be collected automatically and subjected to further analysis. 

At the smallest scale, the silicon photonic wire waveguides that are the subject of this chapter have a silicon core only a few hundred nanometers across and refractive index of n = 3.47 at a wavelength of /. 1550 nm31. Figure 9.3 shows an example... 

The major advantage of this detector is that it is almost universal. All substances have their own characteristic refractive index (it is a physical property of the substance). Thus, the only time that a mixture component would not give a peak is when it has a refractive index equal to that of the mobile phase, a rare occurrence. The disadvantages are that it is not very sensitive and the output to the recorder is subject to temperature effects. Also, it is difficult to use this detector with the gradient elution method because it is sensitive to changes in the mobile phase composition. 

Physical properties of the solvent are used to describe polarity scales. These include both bulk properties, such as dielectric constant (relative permittivity), refractive index, latent heat of fusion, and vaporization, and molecular properties, such as dipole moment. A second set of polarity assessments has used measures of the chemical interactions between solvents and convenient reference solutes (see table 3.2). Polarity is a subjective phenomenon. (To a synthetic organic chemist, dichloromethane may be a polar solvent, whereas to an inorganic chemist, who is used to water, liquid ammonia, and concentrated sulfuric acid, dichloromethane has low polarity.)... 

Ionic liquids are a class of solvents and they are the subject of keen research interest in chemistry (Freemantle, 1998). Hydrophobic ionic liquids with low melting points (from -30°C to ambient temperature) have been synthesized and investigated, based on 1,3-dialkyl imidazolium cations and hydrophobic anions. Other imidazolium molten salts with hydrophilic anions and thus water-soluble are also of interest. NMR and elemental analysis have characterized the molten salts. Their density, melting point, viscosity, conductivity, refractive index, electrochemical window, thermal stability, and miscibility with water and organic solvents were determined. The influence of the alkyl substituents in 1,2, 3, and 4(5)-positions on the imidazolium cation on these properties has been scrutinized. Viscosities as low as 35 cP (for l-ethyl-3-methylimi-dazolium bis((trifluoromethyl)sulfonyl)amide (bis(triflyl)amide) and trifluoroacetate) and conductivities as high as 9.6 mS/cm were obtained. Photophysical probe studies were carried out to establish more precisely the solvent properties of l-ethyl-3-methyl-imidazolium bis((trifluoromethyl)sulfonyl)amide. The hydrophobic molten salts are promising solvents for electrochemical, photovoltaic, and synthetic applications (Bon-hote et al., 1996). 

The effect of particulate additives on the appearance of polymers is a complex subject depending, among other things, on the colour, refractive index, particle... 

The Rayleigh approximation shows that the intensity of scattered light depends on the wavelength of the light, the refractive index of the system (subject to the limitation already cited), the angle of observation, and the concentration of the solution (which is also restricted to dilute solutions). In the Rayleigh theory, the size and shape of the scatterers (M and B) enter the picture through thermodynamic rather than optical considerations. 

Compositions of ABS polymers that contain a special ethylene oxide copolymer have been developed, which do not suffer from these drawbacks. The ethylene oxide copolymer consists of ethylene oxide and 1-naphthyl glycidyl ether. The copolymer a should have a high refractive index of more than 1.50. The presence of this copolymer in the ABS resin composition gives a product of remarkably improved surface appearance when the composition is subjected to injection molding. In addition, the resin composition has an excellent antistatic property (23). 

Venus is completely covered with dense clouds. The composition of the clouds has been the subject of much speculation for many years. It includes ice, carbon suboxide, sulfuric acid, hydrocarbons, mercuric chloride, ammonium chloride, and hydrated ferrous chloride. Recently, Young (1066a) has proposed, based on refractive index measurement, that the clouds are composed most probably of droplets of 75% H2S04. 

What is even more relevant to the present subject is that a thin dielectric layer of polymer can be situated between two media without grossly distorting the optical nature of the interface, i.e. total internal reflection would occur as if no polymer layer is present even if its refractive index is unmatched to both media. Such a layer will, however, affect the intensity of the evanescent wave and particularly its depth of penetration. ... 

Other methods that have been used in determination of the amount of moisture in coke include (1) extraction of coke using anhydrous methanol and the addition of calcium hydride with coal constituents (CaH2) from which the amount of released heat is measured, and (2) extraction of coke using anhydrous dioxan and measurement of the refractive index of the solution to determine its water content. Application of these methods to coal may be subject to error because of (1) interaction of the coal (in contrast to coke) with the calcium hydride, leading to chemical errors, and (2) the influence of extractable constituents on the refractive index of the dioxan. 

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