Distortion index

Orbital distortion index. A positive sign indicates distortion toward the axial direction. 

Figure 7.24. A. Relationship between 8 so values and the summed bond strengths of the oxygen atoms for a number of phosphates. Opien symbols denote orthophosphates, closed symbols denote higher phosphates. From Cheetham et al. (1986), by permission of the Royal Society of Chemistry. B. Relationship between the CSA for several orthophosphates and the geometrical distortion index (DI) of the phosphate group. From data of Turner et al. (1986a).

A better correlation has been demonstrated for the same restricted group of phosphates between the CSA and the distortion index (DI) describing the mean deviation of the PO4 bond angles from ideal tetrahedral symmetry ... 

MacKenzie and Meinhold 1994a), the most promising being between Xq and the distortion index (DI), defined for octahedral bond angles as... 

Figure 8.11. Relationship between the nuclear quadrupole coupling constant xq for a number of magnesium compounds and minerals and A. the octahedral distortion index DI defined in Equation (8.1). Regression line fitted only to the most reliable data points (full circles), less reliable data points (full squares) are included for interest only. B. the octahedral shear strain il defined in Equation (8.2). Regression line fitted to all data points. From MacKenzie and Meinhold (1994a) by permission of the copyright owner.

Figure 18 The correlation of QjC ) versus the generalized local distortion index (Dl) for TiOe, TiOs, and Ti04 units is shown. See Ref. [42] for a comprehensive discussion and formulae regarding the distortion index. Reprinted with permission from Ref. [49]. Copyright 2002 American Chemical Society.

Formulation UL94 V Rating (3.2 mm) Heat Melt Flow Distortion Index (MFI) Temperature (5 kgl230°C) (°C) (g/10 min) Notched Izod Impact (ASTM D256) (JItn)... 

The authors used several octahedral distortion parameters [83], such as shear strain and distortion index, to describe ZrOg octahedra and assign the two Zr SSNMR resonances to crystallographic sites within... 

The amplitude of the input signal is often associated with a distortion index, controlled by an envelope. In this case, changes in volume will cause changes in the spectrum. This coincides in theory with the behaviour of a number of acoustic instruments, where louder playing produces more overtones. 

T and are the glass-transition temperatures in K of the homopolymers and are the weight fractions of the comonomers (49). Because the glass-transition temperature is directly related to many other material properties, changes in T by copolymerization cause changes in other properties too. Polymer properties that depend on the glass-transition temperature include physical state, rate of thermal expansion, thermal properties, torsional modulus, refractive index, dissipation factor, brittle impact resistance, flow and heat distortion properties, and minimum film-forming temperature of polymer latex... 

For thin-film samples, abrupt changes in refractive indices at interfrees give rise to several complicated multiple reflection effects. Baselines become distorted into complex, sinusoidal, fringing patterns, and the intensities of absorption bands can be distorted by multiple reflections of the probe beam. These artifacts are difficult to model realistically and at present are probably the greatest limiters for quantitative work in thin films. Note, however, that these interferences are functions of the complex refractive index, thickness, and morphology of the layers. Thus, properly analyzed, useful information beyond that of chemical bonding potentially may be extracted from the FTIR speara. 

To be successful, molded optical elements of plastics must be produced with careful control of the fabricating process. In the case of these optical products it is particularly important that the molding conditions be carefully controlled to minimize molded-in stress. In addition to these stresses reducing the dimensional stability of the products leading to distorted images, the stresses themselves affect the quality of the image. This is a result of the fact that the stresses/strained areas have a different refractive index from that of the... 

In order to compensate for the distortions in the wavefront due to the atmosphere we must introduce a phase correction device into the optical beam. These phase correction devices operate by producing an optical path difference in the beam by varying either the refractive index of the phase corrector (refractive devices) or by introducing a variable geometrical path difference (reflective devices, i.e. deformable mirrors). Almost all AO systems use deformable mirrors, although there has been considerable research about liquid crystal devices in which the refractive index is electrically controlled. 

From this equation it can be seen that the depth of penetration depends on the angle of incidence of the infrared radiation, the refractive indices of the ATR element and the sample, and the wavelength of the radiation. As a consequence of lower penetration at higher wavenumber (shorter wavelength), bands are relatively weaker compared to a transmission spectrum, but surface specificity is higher. It has to be kept in mind that the refractive index of a medium may change in the vicinity of an absorption band. This is especially the case for strong bands for which this variation (anomalous dispersion) can distort the band shape and shift the peak maxima, but mathematical models can be applied that correct for this effect, and these are made available as software commands by some instrument manufacturers. 

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