Perpendicular polarization-mode electric

Figure 6 ATR setup. Optical and stmctural features are related to the IRE fixed-coordinate system x,y,z. E and E denote the parallel and perpendicular polarized electric field components of the light incident to the IRE under the angle 0,. E results in the , and E components of the evanescent wave, while E results in the Ey component, m denotes the unit vector in direction of the transition dipole moment vector of a given vibrational mode, and Wy, are the corresponding components in the IRE coordinate system, m goes off at an angle a with respect to the z-axis and the projection of mto the xy-plane goes off at an angle

Consider first an anisometric molecule with the longitudinal p, and transversal p, permanent dipole moments in an isotropic phase. There are two relaxation modes mode 1, rotations of p, around the long axis, and mode 2, reorientation of p,. Figure 10-1. The mode 1 has a smaller relaxation time, Tj < Tj, because of the smaller moments of inertia involved. When this isotropic fluid is cooled down into the NEC phase, the dynamics is affected by the appearance of the nematic potential associated with the orientational order along the director n. The mode 1 remains almost the same as in the isotropic phase, and contributes to both the parallel and perpendicular components of dielectric polarization (determined with respect to n). Mode 2 is associated with small changes of the angle between p, and n it contributes to the parallel component of dielectric polarization. Mode 3 is associated with conical rotations of p, around the director (as the axis of the cone) it is effective when the applied electric field is perpendicular to n and contributes... 

Hereby, the branches with E - and / -symmetry are twofold degenerated. Both A - and / d-modes are polar, and split into transverse optical (TO) and longitudinal optical (LO) phonons with different frequencies wto and wlo, respectively, because of the macroscopic electric fields associated with the LO phonons. The short-range interatomic forces cause anisotropy, and A - and / d-modcs possess, therefore, different frequencies. The electrostatic forces dominate the anisotropy in the short-range forces in ZnO, such that the TO-LO splitting is larger than the A -E splitting. For the lattice vibrations with Ai- and F -symmetry, the atoms move parallel and perpendicular to the c-axis, respectively (Fig. 3.2). 

Since the electric field vector of the incident microwave radiation, Emw, is linearly polarized perpendicular to the broad face of the waveguide absorption cell (TEio-mode of propagation), the M-selection rules may be selected by the orientation of the waveguide cell with respect to the magnetic field. This may be... 

Suppose that we irradiate a single crystal of calcite with polarized infrared radiation whose electric vector vibrates along the c axis (z direction) in Fig. 1.42. Then the infrared spectrum shown by the solid curve of Fig. 1.48 is obtained [142]. According to Table 1.21, only the A2 vibrations are activated under such conditions. Thus, the three bands observed at 885(v), 357(0, and 106(r) cm are assigned to the species. The spectrum shown by the dotted curve is obtained if the direction of polarization is perpendicular to the c axis (x,y plane). In this case, only the vibrations should be infrared-active. Therefore the five bands observed at 1484(v), 706(v), 330(0, 182(0, and 106(r) cm are assigned to the species. Here, v, t, and r denote intramolecular, translatory lattice, and rotatory lattice modes, respectively. 

One of the principal analytical techniques used for surface-sensitive and orientational analysis is SFG [1, 22-26]. This nonlinear optical technique is based on a coherent photon emission process. It utilizes a combination of two laser beams, one in the visible and one in the IR range frequency, set at two possible polarizations, p - for light incident parallel to the plane of incidence, and s - for incidence perpendicular to it. The resulting SFG signals emitted from the surface are proportional to the interaction of the molecular vibrational modes with the incoming electric fields and their hyperpolarizabiHties. The emitted signals from the surface are analyzed and interpreted according to their intensities and intensity ratio at the four relevant polarization combinations [24, 27, 28]. 

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