Refractive index and infrared

Germanium dioxide has high refractive index and infrared transmission, for which it is used in industrial glasses. It also is used in preparation of high purity grade germanium. 

Some plasticizer mixes require pretreatment, such as saponification, but in most instances chromatographic separations can be accomplished with the mix. In addition to the usual identification of substances by organochemical analysis, other methods now being used include color tests, physical tests (determinations of boiling point and refractive index), and infrared and ultraviolet spectroscopy. 

Using the more accurate gas chromatographic technique rather than a combination of refractive index and infrared methods to analyse the olefin composition, Saunders et showed that the initial halogeno elimination results... 

Hair after treatment with TGA cumene hydroperoxide using methyl methacrylate monomer was hydrolyzed with 5N hydrochloric acid to dissolve away the keratin from the polymer, and part of the resultant fiberlike residue was dissolved in organic solvents. The solute (in the organic solvents) was shown to be polymethyl methacrylate by refractive index and infrared spectroscopy [87]. 

Microscopy (qv) plays a key role in examining trace evidence owing to the small size of the evidence and a desire to use nondestmctive testing (qv) techniques whenever possible. Polarizing light microscopy (43,44) is a method of choice for crystalline materials. Microscopy and microchemical analysis techniques (45,46) work well on small samples, are relatively nondestmctive, and are fast. Evidence such as sod, minerals, synthetic fibers, explosive debris, foodstuff, cosmetics (qv), and the like, lend themselves to this technique as do comparison microscopy, refractive index, and density comparisons with known specimens. Other microscopic procedures involving infrared, visible, and ultraviolet spectroscopy (qv) also are used to examine many types of trace evidence. 

The sodium chloride (NaCl) crystal shows very high absorption and reflectivity in the infrared region, known as the Restrahlen region. The real and imaginary relative dielectric constants at 6000 nm are, respectively, ei = 16.8 and S2 = 91.4. At this wavelength, estimate (a) the refractive index and the extinction coefficient, and (b) the optical density and the reflectivity at normal incidence for a 1 mm thick NaCl sample, (c) If the previous sample is illuminated (at normal incidence) by a beam of intensity Iq at 6000 nm, estimate the intensity of this... 

Infrared and ultraviolet spectroscopy, including specific optical rotation, refractive index, and Raman spectral analysis... 

Fourier transform infrared microscopes are equipped with a reflection capability that can be used under these circumstances. External reflection spectroscopy (ERS) requires a flat, reflective surface, and the results are sensitive to the polarization of the incident beam as well as the angle of incidence. Additionally, the orientations of the electric dipoles in the films are important to the selection rules and the intensities of the reflected beam. In reflectance measurements, the spectra are a function of the dispersion in the refractive index and the spectra obtained are completely different from that obtained through a transmission measurement that is strongly influenced by the absorption index, k. However, a complex refractive index, n + ik can be determined through a well-known mathematical route, namely, the Kramers-Kronig analysis. 

Potassium titanate has a high refractive index and a low thermal conductivity. Moreover, its size is in the right range to scatter infrared radiation. Thus it has potential use as an insulating and ir-reflective material. Other potential applications of potassium titanate include its use as a filtration medium, a reinforcement material for organic polymers, and an asbestos replacement in friction brakes. Between 1965 and 1972, pigmentary potassium titanate was manufactured in the United States (108). 

The electron effective mass in GaN is now reasonably well established by cyclotron resonance measurements [14-16] asm, = (0.22 0.0 l)m, and the low frequency dielectric constant (appropriately averaged spatially) e(0) = 9.5 0.2, from infrared refractive index and optic phonon energy measurements [17]. We can therefore derive a reliable value for the hydrogenic donor ionisation energy of EDH = (33.0 1.5) meV which compares well with IR absorption measurements, giving Ed = (35 1) meV [18] (see below). The discrepancy is readily explained in terms of a small chemical shift. 

V indicates the principal value) are applied to a function F = F + F" (Bode, 1950 Smith, 1985 Hopfe et al., 1981). Such so-called dispersion relations exist between the (real) refractive index and the absorption index. Dedicated software programs are available, also specially for (infrared) spectroscopic purposes (Hopfe, 1989), a generalization for oblique incidence on layered systems was given by Grosse and Offermann (1991). 

The ellipsometric parameters xl> and A experimentally determined with a homogeneous thick sample, are algebraically related with the components of the dielectric function, which in turn define the refractive index and the absorption index (Bom and Wolf, 1980). The parameters for the strong oscillator used to simulate the spectra shown in Fig. 6.4-5 were chosen to resemble the strong infrared resonance of quartz glass. Radiation reflected from such a sample was measured ellipsometrically the evaluation led to the results presented In Fig. 6.4-14. For weaker absorbers such as many molecular compounds. 

The most common detection techniques are ultraviolet, visible, refractive index, near-infrared and mass flow (density). These detectors are typically available in explosion proof and non-explosion proof electronics. The distance between the detector and the fraction valve and the reaction time of the valve is important when cuts need to be made along sharp front or rear boundaries. 

Nair S and Tsapatsis M. Infrared reflectance measurements of zeolite film thickness, refractive index and other characteristics. Micropor Mesopor Mater 2003 58 81-89. 

First, wc purify the compound and determine its physical properties melting point, boiling point, density, refractive index, and solubility in various solvents. In the laboratory today, we would measure various spectra of the compound (Chap. 13), in particular the infrared spectrum and the nmr spectrum indeed, because of the wealth of information to be gotten in this way, spectroscopic examination might well be the first order of business after purification. From the mass spectrum we would get a very accurate molecular weight. 

On the basis of its physical properties—boiling point, melting point, density, refractive index, and, most reliable of all, its infrared and mass spectra—it may be identified as a previously studied alkane of known structure. 

Refractive index and specific refractive index increments - (k = dn/dc) of polymers in solution have been studied extensively in connection with light scattering measurements and size exclusion chromatography applications to polymer characterization for which refractometers are used as standard concentration detectors. Contrary to the observations made in the infrared region (12), refractive index increments have been shown to be a function of the molecular weight of the polymers (2) and, in some cases, of the copolymer composition (17). Therefore, the assumptions of linearity and additivity (Eq. 1 to 4) have to be verified for each particular polymer system. In the case of styrene/acrylonitrile copolymers, there is an additional uncertainty due to the... 

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