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INDEX dipole

It is important to know the influence of the physicochemical parameters of the mobile phase (dipole moment, dielectric constant, and refractive index) on solvent strength and selectivity. The main interactions in planar chromatography between the molecules of the mobile phases and those of solutes are caused by dispersion forces related to the refractive index, dipole-dipole forces related to the dipole moment, induction forces related to a permanent dipole and an induced one, hydrogen bonding, and dielectric interactions related to the dielectric constant. Solvent strength depends mainly on the dipole moment of the mobile phase, whereas the solvent selectivity depends on the dielectric constant of the mobile phase. [Pg.95]

Dip a2/V Kirkwood-Onsager dipole solvent index [(dipole momentj /volume]... [Pg.613]

Table 6.4 Refraction index, dipole moment, and related solubility parameters for solvents... Table 6.4 Refraction index, dipole moment, and related solubility parameters for solvents...
Snrface or volnme density of molecnles (atoms), nnmber of reflections Refractive index Dipole moment Electric polarization Reflection coefficient Reflectance Oscillator strength Time/transmission coefficient Temperatnre/transmittance Velocity... [Pg.748]

VISCOSITY, SURFACE TENSION, DIELECTRIC CONSTANT, DIPOLE MOMENT, AND REFRACTIVE INDEX... [Pg.449]

Physical Properties. Properties of some alkyl peroxyesters are Hsted in Table 13 and the properties of some alkyl areneperoxysulfonates are given in Table 14. Mass spectra (226), total energies, and dipole moments (227) oxygen—oxygen bond-dissociation energies (44,228) and boiling points, melting points, densities, and refractive indexes (44,168,213) have been reported for a variety of tert-huty peroxycarboxylates. [Pg.127]

Compound CAS Registry Number Boiling point, °C Density at 20°C, g/cm Dipole moment, 10-"° Cm Index of refraction, < PR nmr Parameters chemical t shift, ppm ... [Pg.378]

The dielectric constant is a measure of the ease with which charged species in a material can be displaced to form dipoles. There are four primary mechanisms of polarization in glasses (13) electronic, atomic, orientational, and interfacial polarization. Electronic polarization arises from the displacement of electron clouds and is important at optical (ultraviolet) frequencies. At optical frequencies, the dielectric constant of a glass is related to the refractive index k =. Atomic polarization occurs at infrared frequencies and involves the displacement of positive and negative ions. [Pg.333]

The physical data index summarizes the quantitative data given for specific compounds in the text, tables and figures in Volumes 1-7. It does not give any actual data but includes references both to the appropriate text page and to the original literature. The structural and spectroscopic methods covered include UV, IR, Raman, microwave, MS, PES, NMR, ORD, CD, X-ray, neutron and electron diffraction, together with such quantities as dipole moment, pX a, rate constant and activation energy, and equilibrium constant. [Pg.6]

As shown in Fig. 7, a large increase in optical absorption occurs at higher photon energies above the HOMO-LUMO gap where electric dipole transitions become allowed. Transmission spectra taken in this range (see Fig. 7) confirm the similarity of the optical spectra for solid Ceo and Ceo in solution (decalin) [78], as well as a similarity to electron energy loss spectra shown as the inset to this figure. The optical properties of solid Ceo and C70 have been studied over a wide frequency range [78, 79, 80] and yield the complex refractive index n(cj) = n(cj) + and the optical dielectric function... [Pg.51]

In order to obtain better separations it is very important to know the bulk physical properties of solvents (viscosity, refractive index, dielectric constant, dipole moment. [Pg.68]

The model has the advantage that it requires only a simple table eontaining the polarity index P and selectivity group for a number of solvents (Table 4.2). The model is based on Snyder s elassifieation of solvents [41,42] aeeording to their eharaeteristies to internet as proton aeeeptors (xj, proton donors (x, or dipoles (xj. [Pg.90]

Solvent Boiling Point CO Viscosity (CP) Refractive Index UV Cut-off (nm) Dielectric Constant Dipole Moment (D) Surface Tension (dyne/cm)... [Pg.747]

The general or universal effects in intermolecular interactions are determined by the electronic polarizability of solvent (refraction index n0) and the molecular polarity (which results from the reorientation of solvent dipoles in solution) described by dielectric constant z. These parameters describe collective effects in solvate s shell. In contrast, specific interactions are produced by one or few neighboring molecules, and are determined by the specific chemical properties of both the solute and the solvent. Specific effects can be due to hydrogen bonding, preferential solvation, acid-base chemistry, or charge transfer interactions. [Pg.216]

Figures 13(a) and 13(b) illustrate the intensity distributions for two environment/substrate combinations, namely air/glass and water/glass. It can be concluded that the dipole located at a dielectric surface preferably radiates into the higher refractive index substrate at angles close to the critical angle. The intensity radiated into the environment is, on the other hand, relatively small. Yet it is this fraction of the fluorescence intensity that forms the basis of the sensor signal in conventional systems such as the optical biosensor... Figures 13(a) and 13(b) illustrate the intensity distributions for two environment/substrate combinations, namely air/glass and water/glass. It can be concluded that the dipole located at a dielectric surface preferably radiates into the higher refractive index substrate at angles close to the critical angle. The intensity radiated into the environment is, on the other hand, relatively small. Yet it is this fraction of the fluorescence intensity that forms the basis of the sensor signal in conventional systems such as the optical biosensor...
Fig. 10 ROCSA pulse sequence based on Cn symmetry. The rectangular blocks in black represent jt/2 pulses. The recoupling period (q) comprises k cycles of Cnln. Each complete cycle of Cnln spans n rotor periods (nzR). The rf phase of each Cq subcycle is set equal to 2nq/n, where q is an index running from 0 to n — 1. Within each Cq subcycle, azR and bzR indicate the position and the duration of the POST composite pulse, respectively. We find that the solution (a, b) = (0.0329,0.467) is a favorable choice for the suppression of the homonuclear dipole-dipole interaction. The bracketed and subscripted values indicate the pulse length and rf phase in radians, respectively. (Figure and caption adapted from [158], Copyright [2003], American Institute of Physics)... Fig. 10 ROCSA pulse sequence based on Cn symmetry. The rectangular blocks in black represent jt/2 pulses. The recoupling period (q) comprises k cycles of Cnln. Each complete cycle of Cnln spans n rotor periods (nzR). The rf phase of each Cq subcycle is set equal to 2nq/n, where q is an index running from 0 to n — 1. Within each Cq subcycle, azR and bzR indicate the position and the duration of the POST composite pulse, respectively. We find that the solution (a, b) = (0.0329,0.467) is a favorable choice for the suppression of the homonuclear dipole-dipole interaction. The bracketed and subscripted values indicate the pulse length and rf phase in radians, respectively. (Figure and caption adapted from [158], Copyright [2003], American Institute of Physics)...

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See also in sourсe #XX -- [ Pg.227 , Pg.228 , Pg.229 ]




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