Inhomogeneous electric field

A MBER spectrometer is shown schematically in figure C1.3.1. The teclmique relies on using two inhomogeneous electric fields, the A and B fields, to focus the beam. Since the Stark effect is different for different rotational states, the A and B fields can be set up so that a particular rotational state (with a positive Stark effect) is focused onto the detector. In MBER spectroscopy, the molecular beam is irradiated with microwave or radiofrequency radiation in the... 

Both the ground state and the 67.4 keV nuclear excited state of possess a nonzero electric quadrupole moment. If placed in an inhomogeneous electric field (electric field gradient, EFG 0) the Ni nucleus undergoes electric quadmpole interaction with the EFG at the nucleus, as a result of which the 67.4 keV level will split into three substates /, wi) = 5/2, 5/2), 5/2, 3/2), and 5/2, 1/2) and the ground level will split into two substates 3/2, 3/2) and 3/2, 1/2). 

B. Approaches Based on Ab Initio Calculations on a Single Water Molecule in an Inhomogeneous Electric Field... 

The simple collision theory for bimolecular gas phase reactions is usually introduced to students in the early stages of their courses in chemical kinetics. They learn that the discrepancy between the rate constants calculated by use of this model and the experimentally determined values may be interpreted in terms of a steric factor, which is defined to be the ratio of the experimental to the calculated rate constants Despite its inherent limitations, the collision theory introduces the idea that molecular orientation (molecular shape) may play a role in chemical reactivity. We now have experimental evidence that molecular orientation plays a crucial role in many collision processes ranging from photoionization to thermal energy chemical reactions. Usually, processes involve a statistical distribution of orientations, and information about orientation requirements must be inferred from indirect experiments. Over the last 25 years, two methods have been developed for orienting molecules prior to collision (1) orientation by state selection in inhomogeneous electric fields, which will be discussed in this chapter, and (2) bmte force orientation of polar molecules in extremely strong electric fields. Several chemical reactions have been studied with one of the reagents oriented prior to collision. ... 

The energy of the nuclear electric quadrupole in an inhomogeneous electric field varies with the orientation of the quadrupole moment. The electric field E at a particular nucleus in the molecule is determined by the electronic wave function and the electric fields produced by the other nuclei. There is no reason for E to be constant over the region around any nucleus. Rather, the components of E will vary, and we will have nonzero values of 3 x/dx, 3 x /dy, etc. The electric potential V(x,y,z) at a point (x,y,z) in space can be defined such that E= — grad V, or [Halliday and Resnick, Section 29-7]... 

How can cells be brought into the proper aligment required for electrically induced fusion When cells are placed in an inhomogeneous electric field, as demonstrated in Fig. 49, they start to migrate in the direction of larger field strength. This is caused... 

Fig. 49 a and b. Diagrammatic representation of a neutral particle in an inhomogeneous electric field, a) the particles are able to migrate, because the field intensity is not equal on both sides resulting in a net force so-called dielectrophoresis, b) The direction of dielectrophoresis is independent of the polarity of the field. In an alternating field all particles will move in the direction of higher field strengths 611... 

Depending on the type of boundary and field, a force may act on the static interface. This can be seen from Figure 10-8. For the analysis, let us place the crystal between asymmetric capacitor plates. Without the field, the boundary (b) is surrounded by a symmetric (AX/AX) or an asymmetric (AX/AY) space charge. Thus, an inhomogeneous electric field exerts a force on the (dipolar) interface. The boundary... 

Figure 10-8. Schematic diagram of a device for the determination of interface mobility in an inhomogeneous electric field. The motion due to electric (and frictional) forces occurs a) without, b) with galvanic contact (inducing ionic fluxes and decomposition of AX).

In parallel processes, c.g., field-assisted diffusion and sliding, the bond between the surface and the adatom is never completely broken. Field-assisted diffusion of an adatom on the surface occurs due to the presence of the intense, inhomogeneous electric field between the probe tip and the surface, which gives rise to a potential gradient. 

Electric fields A patterned top electrode generates a laterally inhomogeneous electric field [30], The replication of the electrode pattern is due to two effects. Since the time constant for the amplification of the surface instability scales with the fourth power of the plate spacing (Eq. (1.8)), the film becomes unstable first at locations where the electrode topography protrudes downward towards the polymer film. In a secondary process, the... 

Table VI summarizes observed manifestations of field-generated forces- The field effects may manifest themselves as an orientation of particles in the direction of the field or perpendicular to it or, "pearl chain" formation, i.e., the alignment of particles in the field direction may occur. This has long been considered a mysterious demonstration of microwave induced biological effects. Deformation or destruction of cells can be achieved with fields. The movement of cells in inhomogeneous electrical fields can be affected.

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