Electric field applied

The simplest SCRF model is the Onsager reaction field model. In this method, the solute occupies a fixed spherical cavity of radius Oq within the solvent field. A dipole in the molecule will induce a dipole in the medium, and the electric field applied by the solvent dipole will in turn interact with the molecular dipole, leading to net stabilization. 

The first mechanism is illustrated by Figures 1 to 4. These figures show the calculated non-local conductivity of a system consisting of 10 atomic layers of copper sandwiched between 11 atomic layers of cobalt on either side. The electric field is applied paralle to the planes which causes the current to flow parallel to the planes as well. The figures show the non-local layer depe lent conductivity, 0 1,J), which is the current of spin s electrons induced in atomic layer I by an electric field applied to layer J. 

Figure 16. Simplified schematic of the architecture of a single CCD pixel. The channel stops permanently define the pixel boundaries in the column direction. The pixel rows are defined by the electric fields applied to the three pixel phases. For a 15 /urn pixel CCD, channel stops are 2-3 /um wide and the phases are each 5 /um wide.

Figure 2 Schematic representation of the effect of an external electric field applied along the longitudinal axis of a stereoregular polymer.

Typically, 40 gl of 5.0 M alkyne compoimd and 40 gl of 5.0 M alkyne of the diketo compound were placed in the corresponding reservoirs (Figure 4.70) [8]. The same holds for diisopropylethylamine (40 gl 5.0 M). The electrical fields applied were ... 

Ion-exchange processes can be driven by concentration gradients or by an electric field applied across the membrane (electrodialysis), the ions not merely being exchanged but actually passing across. 

The solution to be electrosprayed is passed through the electrospray capillary (ESC) by means of a motor driven syringe. Some of the spray containing the ions then enters the pressure reducing capillary (PRC) leading to the forechamber (FCH) of the ion source. The exit tip of the PRC directs the gas jet in a direction parallel to the bottom of the FCH, i.e. across the interface plate (IN). An orifice of 4 mm diameter in the interface plate connects the FCH to the reaction chamber (RCH). The ions in the jet exiting from the PRC are deflected out of the jet towards this orifice and into the RCH by means of an electric field applied across the FCH. A weak field is also applied across the RCH. At the bottom of the RCH a small orifice, 100 pm diameter, allowed some gas and ions to leak into the vacuum of the mass... 

A modified technique consisting of an electric field applied perpendicular to a flowing buffer solution and using chromatography paper as support(cross-electrophoresis) has been exploited to study the reaction of neomycin with heparin 9 184. Evidence for the formation of a neomycin-heparin complex was obtained by this means. 

The number of cells captured using the MCLW with the electric field applied for 2 min was found to be equal to the number of bacteria captured in 1 h using the same concentration of bacteria but with no applied electric field. Thus, the electric field gave a 30-fold faster response time. The limit of detection was found to be 1 x 103 cells per mL when the electric field was applied for 2 min. This value has been... 

An external electric field applied to the semiconductor also causes a change in its adsorptivity and catalytic activity (Sec. VIII,B). This is the result of a mechanism similar to the preceding case the field causes a change in the surface concentrations of the free electrons and holes. 

The foregoing expression applies only to ions at a concentration approaching 0 and in a nonconductive solvent. Polyionic molecules are surrounded by a cloud of counterions that alter the effective electric field applied on the ions to be separated. This renders the previous expression a poor approximation of what really happens in an electrophoretic apparatus. 

The second parameter influencing the movement of all solutes in free-zone electrophoresis is the electroosmotic flow. It can be described as a bulk hydraulic flow of liquid in the capillary driven by the applied electric field. It is a consequence of the surface charge of the inner capillary wall. In buffer-filled capillaries, an electrical double layer is established on the inner wall due to electrostatic forces. The double layer can be quantitatively described by the zeta-potential f, and it consists of a rigid Stern layer and a movable diffuse layer. The EOF results from the movement of the diffuse layer of electrolyte ions in the vicinity of the capillary wall under the force of the electric field applied. Because of the solvated state of the layer forming ions, their movement drags the whole bulk of solution. 

Electroosmosis refers to the movement of the liquid adjacent to a charged snrface, in contact with a polar liquid, under the influence of an electric field applied parallel to the solid-liquid interface. The bulk fluid of liquid originated by this electrokinetic process is termed electroosmotic flow. It may be prodnced either in open or in packed or in monolithic capillary columns, as well as in planar electrophoretic systems employing a variety of snpports, such as paper or hydrophilic polymers. The origin of electroosmosis is the electrical donble layer generated at the plane of share between the snrface of either the planar support or the inner wall of the capillary tube and the surronnding solntion, as a consequence of the nneven distribntion of ions within the solid/liquid interface. 

In the absence of EOF and separation mechanism other than electrophoresis, each analyte migrates with its own velocity which, according to Equation 6.8, is proportional to the strength of the electric field applied across the capillary tube. The constant of proportionality of the observed velocity of the charged analyte is defined as the observed mobility (p bs) and can be directly calculated by the migration time and the other experimental parameters, according to the following equation ... 

A cheaper and more sensitive mass spectrometer than a magnetic sector instrument is based on the quadrupole analyser (Fig. 9.2), which uses two electric fields applied at right angles to each other, rather than a magnetic field, to separate ions according to their m/z ratios. One of the fields used is DC and the other oscillates at radiofrequeney. 

J,m. The electric field applied is also simply calculated by dividing the applied voltage directly measured on the instrument by the distance between the electrodes. The effective inter-electrode distance is obtained by measuring the conductance of a standard electrolyte solution, say... 

Just as materials have a response when placed in an electric field, they can have a response when placed in a magnetic field. We will see in this section that many of the concepts of permanent dipoles and dipole alignment in response to an applied field that were described in the context of electrical fields apply to magnetic fields as well. There are a few differences, however, and we will also see that there are fewer materials with specialized magnetic properties than there were with specialized electrical and electronic properties. The magnetic properties of materials are nonetheless important, and they are applied in a number of technologically important areas. 

The band structure depicted is for the junction in the dark and with no electric field applied. Now suppose that an electrical field is applied so that the / -type is made negative relative to the p-type (i.e., in the reverse direction to the applied voltage in transistors see Chapter 4). Electrons will then flow from the / -type to the p-type. An electron in the conduction band moving to the p-type side can drop down into one of the... 

An electric field applied across the p-/i junction, as in LEDs, produces an excess of electrons in the conduction band of the gallium arsenide. These electrons do not drift... 

From microwave spectra, in the presence of a uniform electric field applied to the gas (Stark effect), it is possible to obtain accurate measurements of dipole moments. 

The scanning system is a very important part of these microscopes, and is commonly composed of a cantilever whose arms are usually made of piezoelectric quartz crystal. The electric field applied by the computer to the arms of the scanning device controls the position of the tip of the sensor to within a great spatial precision. The right variation of the electric field allows the complete scanning of the sample. 

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