Dipole direction

Only at extremely high electric fields are the water molecules fiilly aligned at the electrode surface. For electric fields of the size normally encountered, a distribution of dipole directions is found, whose half-widtli is strongly dependent on whether specific adsorption of ions takes place. In tlie absence of such adsorption the distribution fiinction steadily narrows, but in the presence of adsorption the distribution may show little change from that found at the PZC an example is shown in figure A2.4.10 [30]. 

Our method has evolved during many studies over the last two decades. These include studies on the effect of strong internal electric fields in crystals on optical transition dipole directions of nucleic acid bases [2, 3], QM-MM predictions of time-dependent solvatochromism on 3-methylindole (3MI) in water [4], and on tryptophan in several proteins [5-8]. More recently, the same techniques have been... 

Fig. la, b. Schematic depiction of the two most common crystalline chain conformations in PVF2 a. tg+ tg and b. all-trans. The arrows indicate projections of the -CF2 dipole directions on planes defined by the carbon backbone. (Figure and caption from Ref. [32])... 

Directions of bond dipole Direction of molecular moments in CH3C1 dipole moment... 

Fig. 1. H-bonds in the crystal cell of TKHS-like crystal the sign (+) relates to covalently bonded oxygen and (-) to hydrogen-bonded one. The positive signs of all pseudospins chosen to correspond the dipole directions of H-bonds.

Molecules with peripheral dipoles are directed with these dipoles to negative spots of the surface, as discussed in Secs. V,5 and VI,2 and 5. Such molecules may erect each other so as to leave the dipoles directed to the surface and the rest of the molecules, being parallel to each other, pointing away from it (188). We shall not discuss these points in this article but only remark that they may be of great importance for the understanding of some selective catalytic processes. 

In the actual CO crystal, represented in Figure 17.1 (b) as a randomly oriented (and therefore disordered) mixture of molecules in which, although aligned, both possible dipole directions are presented so that approximately half point one way and the other half point in the opposite direction. In this (real) case each individual CO molecule therefore, can acquire one, of the two dipole orientations and for 1 mole of CO - which contains L molecules, where L is Avogadro s constant - the number of possible arrangements (see Note 17.2) will then be 2L so that the entropy at 0 K is predicted, by Boltzmann s equation to be ... 

Polarizability goes as the cube of radius The electrostatic potential set up by a dipole of moment /xclipoie has the form (/dipole A2) cos (), where () is the angle between the dipole direction and the line to the position where the dipole potential is being sensed.5 For example, a metallic sphere of radius a placed in a constant external electric field Eo... 

Further insight into the charge transfer features was recently obtained44 through single-crystal polarized optical studies of plastocyanin. In these experiments, absorption spectra were obtained (Fig. 14) with polarized light which had its electric dipole direction oriented parallel and perpendicular to the crystal a axis (Fig. 15). These spectra were... 

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