Normal refractive index

The real part of this nnmber is the normal refractive index n = c/v(c and v being the speed of light in vacnnm and in the medium, respectively). The imaginary part of the complex refractive index, k, is called the extinction coefficient. It is necessary to recall here that both magnitndes, n and k, are dependent on the frequency (wavelength) of the propagating wave co,N = N(co). 

It is known that measnring the absorption coefficient (and thns the extinction coefficient) over the whole freqnency range, 0 < real part of N(co) - that is, the normal refractive index ( >) - can be obtained by nsing the Kramers-Kronig relationships (Fox, 2001). This is an important fact, because it allows us to obtain the frequency dependence of the real and imaginary dielectric constants from an optical absorption experiment. 

For comparison of different photochromic materials it is useful to define a normalized refractive index difference, n0, by... 

Figure 13. Calculated normalized refractive index change produced by the dimerization of anthracene, and of various other compounds, as functions of wavelength. Molecular structures, absorption spectra, and further details are given in ref. 28.

Ellipsometric measurements were carried out on LB films of [tetrakis-(3,3-dimethyl-l-butoxycarbonyl)] CuPc in the presence of dry air, toluene, and tetrachlo-roethene. The relative thickness, the normalized refractive index, and extinction coefficient at a fixed wavelength were changed, when these films are exposed to different concentrations of toluene and tetrachloroethene [46],... 

Figure 1 also shows a typical example of refractive index distribution in the GI POFA preform rod measured by an interferometric technique (10, 11), where Uq and n mean the refractive indices at the center axis and at distance r, respectively. As shown in the curve of Figure 1, the preform rod has a cladding region coming from the PMMA tube and a quadratic index profile in the core region. The normalized refractive index distribution of the GI POFA was almost the same as that of this preform rod (12),... 

These formulae become more comprehensible when the factor [m + (A/p)/] = ( e) (m + A /) is considered in more detail. It can be shown that (m + A /) is nearly unity, except for the first wave in the region A 1. This means that wi + (A/p)/ is nearly the normal refractive index. 

Consider the reflection of a normally incident time-harmonic electromagnetic wave from an inhomogeneous layered medium of unknown refractive index n(x). The complex reflection coefficient r(k,x) satisfies the Riccati nonlinear differential equation [2] ... 

The index of refraction of most polymers is greater parallel to the chain than normal to the molecular axis. Substances showing this anisotropy of refractive index are said to be birefringent. 

Hydrocarbon CAS Registry Number Eree2ing point, °C Normal bp,°C Liquid density, kg/m at 20°C Liquid refractive index, A B C range, K... 

A paraffin wax is a petroleum wax consisting principally of normal alkanes. MicrocrystalHne wax is a petroleum wax containing substantial proportions of branched and cycHc saturated hydrocarbons, in addition to normal alkanes. SernimicrocrystaUine wax contains more branched and cycHc compounds than paraffin wax, but less than microcrystalHne. A classification system based on the refractive index of the wax and its congealing point as... 

Wavelength is in units of nm. /n = normalized second order susceptibiUty with refractive index. 

The refractive index detector, in general, is a choice of last resort and is used for those applications where, for one reason or another, all other detectors are inappropriate or impractical. However, the detector has one particular area of application for which it is unique and that is in the separation and analysis of polymers. In general, for those polymers that contain more than six monomer units, the refractive index is directly proportional to the concentration of the polymer and is practically independent of the molecular weight. Thus, a quantitative analysis of a polymer mixture can be obtained by the simple normalization of the peak areas in the chromatogram, there being no need for the use of individual response factors. Some typical specifications for the refractive index detector are as follows ... 

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