Electric field coupling

In the operation of ferroelectric liquid crystal devices, the applied electric field couples directly to the spontaneous polarisation Ps and response times depend on the magnitude E Ps. Depending on the electronic structure (magnitude and direction of the dipole moment as well as position and polarity of the chiral species) and ordering of the molecules P can vary over several orders of magnitude (3 to 1.2 x 10 ), giving response times in the range 1-100 ps. 

One of the applications of TRXRD is to study complex systems where electric fields couple to multiple degrees of freedom. Though femtosecond laser pulses can generate THz radiation from ferroelectric LiTa03, the corresponding lattice motion remained undetected by optical measurements. Cavalleri and coworkers demonstrated the coherent modulation of the X-ray intensity at 1.5 THz [10], and assigned it as phonon-polariton mode of A symmetry (Fig. 3.3). Nakamura and coworkers detected the coherent LO phonon of CdTe... 

Objects having a dipole can be set into rotational motion by applying a torque by means of an electric field [95], Electrorotation is the rotation of particles as a consequence of the induction of dipole moments and torque exertion by a rotating electric field. Coupled electrorotation (CER) uses static external fields which are spatially fixed to induce dipoles in two or more adjacent particles. This creates oscillating components of the electric field, finally resulting in a rotating electric field (for more details, refer to the original literature [95]). 

Principle. Corroding and passive rebars in concrete show a difference in electrical potential of up to 0.5 V, thus a macrocell generates and current flows between these areas (Chapter 8). The electric field coupled with the corrosion current between corroding and passive areas of the rebars (Figure 16.4) can be measured experimentally with a suitable reference electrode (half-cell) placed on the concrete surface, resulting in equipotential lines (potential field) that allow the location of corroding rebars at the most negative values [5-8]. 

It has been found that, as a positively charged oxide particle with a double layer of counterions or lyosphere moves toward the cathode in an EPD cell, the electric field coupled with the motion of the charged particle through the liquid causes a distortion of the double-layer envelope, i.e., the envelope becomes thinner ahead of and thicker behind the particle [181]. Kinetics of EPD is important for controlling the thickness of the deposited layers. There are two modes to operate the system (i) constant-voltage and (ii) constant-current. In constant-voltage EPD, the voltage... 

High-Frequency Electric Field Coupling to Tissue... 

When the applied electric field is directed along the long axis of the ellipsoid, a further enhancement of the electric field in the space between the ellipsoids and a red shift of the resonance frequency take place due to the strong electric field coupling that cannot occur when the electric field is directed along the short axis. This coupling, which is called surface plasmon resonance (SPR), broadens the surface plasmon modes at IR wavelengths [294, 349, 350,404] and promotes the SEIRA effect. 

To estimate the contribution of SPR in the SEIRA, Osawa and coworkers [382, 384,407] modeled the electric field coupling between the particles within the framework of the EMT. The optical constants of the effective medium, which consists of the Ag oblate ellipsoids with p-nitrobenzoate shells and the... 

Consider first the case of parallel fields. The lowest magnetically trappable state of CaD is N = 0,Mj = Q Ms = ). Electric fields couple this state with the rota-tionally excited state N = 1,Ma = 0,Ms = which is in turn coupled with the spin-down state N = l,Mj = l Ms = — ) via the spin-rotation interaction. The matrix representation of Hamiltonian 4.2 in the basis of the three states is... 

Electric Field Coupling to Slow Elastic Modes in Gels of Conjugated Polymers", Phys. Rev. Lett., 53 469-472. 

Elasticity of Poly (diacetylene) Gels Measurements by Electric Field Coupling", Macromolecules, 19, 676-68I. 

---