Water optical anisotropy

Wetzel, R., Zirwer, D., Becker, M. Optical anisotropy of oriented deoxyribonucleic acid films of diffi-rcrit water content. Biopolymers 8 (1969) 391-401... 

This has been explained through the fact that the scattering amplitude is proportional to the optical anisotropy correlation function, a quantity which the breaking of a hydrogen bond modulates in time, a process that affects the optical anisotropy of water. We see, therefore, that the linewidth is the inverse of the average lifetime of the hydrogen bond. 

In many of these studies the structure of the middle phase is not established, but it is clearly immiscible in water or oil and its electrical conductivity is closer to water than oil. Phase diagram studies of oil-water-emulsifier systems Ekwall, (5), indicate that surfactant-rich phases immiscible in oil or wa"ter have rodshaped or lamellar micelles with some degree of optical anisotropy or flow birefringence, and these phases have much greater elec-rical conductivity than oil. Figure 1 illustrates that the middle phase composition varies smoothly from a water-rich composition to an oil-rich composition as the emulsifier partition changes from mostly water-soluble to mostly oil-soluble. If lamellar structures are present the relative thickness of oleophilic and hydrophilic layers must vary smoothly from the water-rich compositions to the oil-rich compositions. 

Table 3 Hsts hydrodynamic parameters of 2M5VP-MAA copolymers of different composition [38]. At a 90 mol% content of 2M5VP imits atpH=1.2 the optical anisotropy of the polyampholyte is negative in sign and approaches the po-ly(2-methyl-5-vinylpyridine) anisotropy value. A change of the anisotropy sign from negative to positive is observed in the alkaline region. This indicates the formation of compact particles at pH=13,stabilizedby the hydrophobic interactions of methyvinylpyridine groups composing the nuclei of the particles. In this case the polyampholyte macromolecule is protected from the precipitation due to hydrophilic carboxylic groups associated with water molecules.

This is found to be a consequence of the optical anisotropy of the AOT molecules [7], which are all aligned orthogonal to the water/oil interface. Negative birefringence is observed also for small droplets stabilized by other amphiphiles [38,44]. 

Fig. 11. Polarized light micrograph showing the bicontinuous pcrcolaing structure developed by SD for the PP/EPR mixture (50/50 wi/wl) unmixed at 200 C for 20 min. and subsequently crystallized by quenching the mixture in an ice-water bath (polarizer and analyzer l ing set in vertical and horizontal directions). Note that the percolating PP-richdomains contain the volume-filling spheruliltes and have high optical anisotropy. From N. Inaba, T. Yamada, S. Suzuki, and T. Hashimoto (1988).

At the beginning of the Gap the water content of the system is not enough to allow a definite structural liquid-crystalline configuration, but the structured entities, within the system, may be indeed oriented and spatially ordered by means of an impressed electric field. Therefore a Kerr-like effect can be observed, due to the optical anisotropy induced by the field. 

The nickel(II) dithiocarbamate complexes are neutral, water-insoluble, usually square-planar, species, and they have been studied extensively by a range of physical techniques. The usual methods for the synthesis of dithiocarbamate complexes have been employed in the case of Ni(II), Pd(II), and Pt(II). In addition, McCormick and co-workers (330,332) found that CS2 inserted into the Ni-N bonds of [Ni(aziri-dine)4P+, [Nilaziridinelgf, and [Ni(2-methylaziridine)4] to afford dithiocarbamate complexes. The diamagnetic products are probably planar, but they have properties typical of dithiocarbamate complexes, and IR- and electronic-spectral measurements suggested that they may be examples of N,S-, rather than S,S-, bonded dithiocarbamates. The S,S-bonded complexes are however, obtained, by a slow rearrangement in methanol. The optically active lV-alkyl-iV(a-phenethyl)dithio-carbamates of Ni(II), Pd(II), and Cu(II) (XXIV) have been synthesized, and the optical activity was found to be related to the anisotropy of the charge-transfer transitions (332). 

From the simulations, we conclude that two hydrogen bonding force constants are a basic requirement for reproducing the measured spectrum. If a water-water potential generates sufficiently large force constant differences for the different proton configurations (or the different relative dipole-dipole orientations in water or ice), it should produce the same effect as seen in the LR model. The anisotropic properties of the classic potentials are a result of charge interaction and this anisotropy should increase in the polarisable potentials and hence they produce a broad optic peak. This broad peak indicates that the orientational variation of the potential function has been increased considerably but it may still be less than the critical value of 1.5 as we indicated in the section 6.1. One would, therefore, expect that a better polarisable potential would, eventually, be able to reproduce the split optic peaks in the measured INS spectrum. 

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