Refractive index dependence

Were it not for dispersion—the refractive index depends upon wavelength— the aesthetic appeal of rainbows would be greatly diminished. Indeed, the word rainbow used in everyday speech evokes images of a profusion of colors—the colors of the rainbow—rather than just an intensely bright arc in the sky. If we take m = 1.343 as the refractive index of violet light (X — 0.4 jam) and m = 1.331 as the refractive index of red light (X = 0.65 jam) (Irvine and Pollack, 1968), then the angular widths of the primary and secondary rainbows are about 1.7° and 3.1°, respectively. 

Use of the differential refractometer detector is applicable to all polymers having refractive indices different from that of the solvent. However, a correction must be made if the polymer refractive index depends on molecular size, such as at very low molecular weights. 

The first point to be made is that in a crystal the refractive index depends not on the direction in which the electromagnetic waves are travelling but on the direction of the electrical disturbances transverse to the line of travel—the vibration direction . We have to consider the shape of the graph connecting refractive index with vibration direction for each crystal system, and the methods available for measuring the refractive indices of crystals in different vibration directions. 

No carbon was recorded for the D-treated film. The O/Si composition ratio was found to be 2.08 and is attributed to the extent of condensation as the organic phase has been removed completely. Based on the amount of Si for sample D and assuming a density of 2.3 g cm3 for amorphous SiC>2, the top layer would correspond to a thickness of 154 nm, if a dense layer is assumed. As the actual layer thickness is 458 nm, this would imply a porosity of 66%. Here a considerable discrepancy with the porosity obtained from ellipsometry is evident. In this respect it should be noted that the RBS measurement was done more to the edge of the sample than ellisometry, where the thickness is smaller than in the centre. Further, the refractive index determined with ellipsometry is very accurate. However, the relation of porosity with refractive index depends on the model used. 

R. S. Knox and H. van Amerongen., Refractive index dependence of the Forster resonance excitation transfer rate, J. Phys. Chem. B, 106 (2002) 5289-5293. 

The anisotropy itself may be linear or circular, or a combination of both. In linear anisotropy the refractive index depends on the direction of polarised light. It is found in solid polymers under tension and in viscous polymeric liquids during flow (shear and elongation). The refractive index can also depend on the chirality of polarised light in this case one speaks of circular or elliptic anisotropy. Thus the so-called "optical activity" is circular birefringence its extinction analogue is circular dichroism. 

Most aerosol materials will vary in their refractive index depending on the wavelength of light used, their chemical composition, and, in some cases, their orientation with respect to the light source and receptor. Since complex indices of refraction are not well established for most materials (Deirmendjian, 1969), optical models of aerosols may contain errors because of the uncertainty of these values. 

We hate using expressions like it can be shown that, but we don t have room to explain everything. If you keep in mind that the refractive index is related to the phase shift as a result of combining die light scattered in the forward direction with the incident beam, then it makes physical sense that the refractive index depends on the polarizability. 

Table 1. Refractive index depending on different organic moieties in the spacer between inorganic and organic backbone...

Mock, J. J., Smith, D. R. and Schultz, S. (2003). Local refractive index dependence of plasmon resonance spectra from individual nanopaiticles. Nano Lett y. 485-491. 

The physical properties, such as melting points, specific heat, viscosity, density, and refractive index depend on the type of fatty acids present in the triglyceride and their location, chain length of fatty acids, number and location of cis and trans double bonds on the fatty acid chains as well as compatibility of the different triglycerides in the mixture and the type of crystal present. 

This correlation is unsurprising. The refractive index depends upon the density of atoms in a crystal. In cubic crystals the atom density averages to be the same in all axial directions while in crystals of lower symmetry some axial directions contain more atoms than others. 

The next detector often used in liquid chromatography is the refractive index detector. This detector uses the property of the sample molecules to bend or refract light. The disadvantage of these detectors in comparison to UV detectors is that refractive index detectors are less sensitive than the UV detectors. Refractive index depends strongly on the temperature of the sample. This is why the refractive index detector must be well thermally insulated. A scheme of the analysis cell of the refractive index detector is shown in Figure 2.23. 

In nonpolar solvents, Eu chelates studied in the present work exhibited luminescence kinetics closely following the single exponential decay law over the intensity range of about three orders of magnitude. In agreement with the previous observations [5, 6], an increase in the refractive index of the nonpolar medium leads to a systematic decrease in the excited-state lifetime of the Eu ion. This effect is accounted for by the well-known refractive-index dependence of the radiative rate y where and are radiative rates in a dielectric medium and in vacuo, respectively, n is the refractive index of the medium, and/[ ) is the local-field correetion factor [4, 5]. 

Dispersion will result if the light source is not strictly monochromatic. An initially sharp pulse consisting of a group of wavelengths will spread out as it travels down the fibre, because the refractive index depends on wavelength. Thus, different wavelengths will travel at different speeds. This effect is known as wavelength dispersion. 

Increased polarizability means increased X and hence lowered speed of propagation. The ratio of the velocity in free space to that in the medium is the refractive index. The detailed calculation shows that the refractive index depends upon the relation between V, the frequency of the light, and the hv corresponding to the various transitions between stationary states in the atom. Hence it is a function of the light frequency. This is the phenomenon of dispersion. 

This electromagnetic (shock) wave is the radiation that was first observed by Cerenkov. It is a classical electromagnetic effect that depends solely on the velocity of the particle and the index of refraction of the material. The refractive index depends upon the wavelength (or frequency) of the light, and the effect occurs only for those wavelengths that give real values of the angle in Eq. (23.I)... 

Figure 1. Refractive-index dependence of the polymers on wavelength. benzyl benzoate doped PMMA PMMA dibutyl phthalate doped partially fluorinated polymer A partially fluorinated polymer.

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