Dipole moment alignment

Figure 12-5 illustrates the solvation of Na and Cl" ions as NaCl dissolves in water. A cluster of water molecules surrounds each ion in solution. Notice how the water molecules are oriented so that their dipole moments align with charges of the ions. The partially negative oxygen atoms of water molecules point toward Na cations, whereas the partially positive hydrogen atoms of water molecules point toward Cl" anions. 

Over the last years we have explored several advanced techniques for high-resolution rotational coherence spectroscopy (RCS [1]) in order to study the structures of molecules and clusters in the gas phase [2]. We have provided spectroscopic examples demonstrating (i) mass-selectivity (Fig. 1, [3]), (ii) that the rotational constants of the ground and electronic excited states can be obtained independently with high precision (lO MO"5, [4]), (iii) that the transition dipole moment alignment, (iv) centrifugal distortion constants, and (v) information on the polarizability tensor can be obtained (Fig.l, [5]). Here we review results pertaining to points (i), (ii), (iv) and (v) [2,3,5],... 

These monoliths were then irradiated with linearly polarised light, causing only those template molecules having a transitional dipole moment aligned with that of the light source to photoreact with the polymer backbone within the MIP binding site. This is shown schematically in Fig. 20.3. 

I. Novel network polyurethane with azobenzene dye in the main frame, Macromolecules, 1995, 28, 6437 Nonlinear optical polymers. 2. Novel NLO linear polyurethane with dipole moments aligned transverse to the main backbone, Macromolecules, 1996, 29, 592. 

This expression illustrates the basic physics of the quantum mechanical dipole. First, there are necessarily two states (or more) involved. One state decreases in energy as the field is turned on, representing the normal case where the electron moves to negative z and the electric dipole moment aligns with the field. The other state. 

Liquid crystals can be composed both of polar and apolar molecules. An important fact in connection with polar substances is that in uniaxial phases there is no polar ordering of the molecules. In average the dipole moments aligned in a given direction are compensated by those aligned in the opposite direction. As a consequence no spontaneous macroscopic polarization develops. More generally one can state that rotation of the director by n does not affect the physical state of the liquid crystal. In biaxial phases built of chiral molecules, such as the chiral smectic C phase, the situation is different. In these systems the compensation of the dipole moments is not perfect, a macroscopic polarization appears in the direction perpendicular both to the layer normal and the director. These phases are therefore ferroelectric. Ferroelectric liquid crystals are currently perhaps the... 

Microwave range Molecules with permanent polar dipole moment align... 

This is sufficient for us to conclude that the symmetric stretch will lead to an absorption band and also that this absorption is due to a transition dipole moment aligned with the Z-axis in the standard symmetry setting. The physical interpretation of this result can be understood from a diagram of H2O in the standard setting, such as Figure 6.3. As O is more electronegative than H, both O—H bonds will have local dipole moments pointing from O toward H. In the Ai vibration the O—H bonds move in phase, and so the Y-components of these dipoles, which are in opposite directions to one another, always cancel out. However,... 

The values refer to the water monomer in the xy plane with the permanent dipole moment aligned with the x axis. 

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