Depolarization coefficients

Consider now the depolarization coefficients. From the explicit form of the expansion of the Cartesian components of the polarization tensor < (, afy, and with respect to the spherical one... 

However, in this case, as already mentioned, pseudovector scattering is also possible. This results in unusual depolarization coefficients not... 

The intensities of the spectral lines and the depolarization coefficients are functions of the reduced matrix elements of the polarizability tensor calculated by vibronic functions. In order to estimate the possibility of observation of the pure rotational Raman spectra under consideration, one has to consider in more detail the polarizability operator. Its components belonging to the line y of representation f can be presented in the form of a power series with respect to the displacement qriri active in the Jahn-Teller effect (the other components can be neglected as not active in the pure rotational Raman spectrum under consideration) ... 

By means of these relations the depolarization coefficient of the light scattered into the second harmonic can be presented in the form... 

Using Eqs. (164), (117), and (145) for the depolarization coefficient of the scattering into the third harmonic at the wing of the line, we have... 

In the case of molecules with cubic symmetry in a ground nondegenerate state of A type, G2(3w, Aw) = 0 and A3 = f. In degenerate states Ti, T2, and G3/2, the depolarization coefficients are less than and depend on frequency, since GiPw, Aw) and G4(3w, Aw) have different spectral width. Therefore the spherical-top molecules seem to be most convenient... 

In analogy with the depolarization ratio for linearly polarized light, the ratio of the two above quantities is known as the reversal coefficient, R(Q, given by... 

Tao T 1969 Time-dependent fluorescence depolarization and Brownian rotational diffusion coefficients of macromolecules Biopolymers 8 609-32... 

The same information may be obtained from purely rotational far infrared spectroscopy (FIR) and depolarized Rayleigh spectra. Dielectric relaxation measurements are also used for the same goal, most successfully in combination with far-infrared data. The absorption coefficient of a periodic electric field... 

Figure 2. Dose-response curve of membrane depolarization as a function of PbTx-3 concentration (7). Data from a total of 22 axons were pooled each axon received only one dose. Data are plotted as means of depolarization amplitudes. TTie solid line is a theoretical 3rd order fit with an ED.q of 1.5 nM, maximum observed depolarization of 30 mV, and a Hill s coefficient of 2.

Benzoic acid derivatives also altered the electrical potential across the cell membrane in neurons of the marine mollusk Navanax lnermls (46). Salicylic acid (1-30 mM) caused a depolarization very rapidly (1-2 min) and decreased the ionic resistance across the membrane. As pH was decreased, more salicylic acid was required to reverse the effect of pH on the membrane potential (47). This result is contradictory to the influence of pH on the amount of salicylic acid required to affect mineral absorption in roots (32). The ability of a series of salicylic and benzoic acid derivatives to increase PD correlated with their octanol/water partition coefficients and pKa values (48). The authors proposed that the organic acid anions bound directly to membranes to produce the observed results. 

Figure 5. Relationship of depolarization of membrane electrical potential (E) in excised roots of barley 250 flM benzoic acids against their partition coefficients (log P). The numbers correspond to specific benzoic acid derivatives (1) salicylic, (2) -hydroxybenzoic, (3) protocatechuic, (4) gentisic,...

The diffusion coefficient of the depolarizer in any supporting electrolyte is determined using a McBain-Dowson cell and the King-Cathard equation. 

Equation 3.13 predicts a linear dependence of In / on E whose slope depends on the coefficient ana, while the ordinate at the origin depends on the electrochemical rate constant and the net amount of depolarizer deposited on the electrode. Accordingly, both the slope and the ordinate at the origin of Tafel plots become phase-dependent [133, 183]. Since the quantity of depolarizer varies from one... 

Today generator matrices F are known for many properties,10 among them the population of different conformers, the relative stability of macromolecular diastereoisomers, the mean-square end-to-end distance, the radius of gyration, the molecular dipole moment, the molecular optical anisotropy (and, with it, the stress-optical coefficient, the Kerr effect, depolarized light scattering, and the... 

Flory has recently summarized the experimental evidence pertaining to local correlation and their effects on chain dimensions (49). There is experimental support for local alignment from optical properties such as stress-optical coefficients in networks (both unswelled and swelled in solvents of varying asymmetry), and from the depolarization of scattered light in the undiluted state and at infinite dilution. The results for polymers however, turn out to be not greatly different from those for asymmetric small molecule liquids. The effect of... 

U. Bafile, L. Ulivi, M. Zoppi, M. Moraldi, and L. Frommhold. The third virial coefficients of collision-induced, depolarized light scattering of hydrogen. Phys. Rev. A, 44 4450, 1991. 

Circular dichroism arises from the same optically active transitions responsible for the Cotton effects observed in ORD curves, but unlike ORD it is an absorption, not a dispersion, phenomenon. Hence, the CD effect is restricted to the region of the transition and can be interpreted more straightforwardly. Both ORD and CD can best be understood if one imagines the incident plane-polarized beam resolved into two in-phase circularly polarized beams whose vectors rotate in opposite directions. A difference in index of refraction between the left and right circularly polarized beams results in rotation of the transmitted plane polarized beam while differential absorption of the two circularly polarized beams results in depolarization of the transmitted beam, so that an incident plane-polarized beam whose frequency is within that of an optically active absorption band becomes both rotated and elliptically polarized upon passage through the sample. This depolarization effect is CD, and the measured parameter is (et — er), the difference in extinction coefficient between the left and right circularly polarized beams. The data is usually recorded as the specific ellipticity, defined as ... 

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