Local electrical properties

Sturm H, Stark W, Bovtoun V, Schulz E (1996) Methods for simultaneous measurements of topography and local electrical properties using scanning force microscopy. In Shanghai, Xia Z, Zhang H (eds) Ninth International Symposium on Electrets (ISE9). IEEE, Piscataway, p 223... 

These phenomena can be better imderstood when the local electrical properties are characterized using a spatially resolved impedance technique. 

A two-phase bulk pol)rmer structure—this interpretation is typical of dielectric spectroscopy analysis of polymers where "more conducting" and "more insulating" segments are expected to display very different electrical properties. As will be shown later, in the literature this interpretation has often evolved into a number of "spatial distributed" or "temporal distributed" film theories based on differences in the localized electrical properties of various film segments. 

IHP) (the Helmholtz condenser formula is used in connection with it), located at the surface of the layer of Stem adsorbed ions, and an outer Helmholtz plane (OHP), located on the plane of centers of the next layer of ions marking the beginning of the diffuse layer. These planes, marked IHP and OHP in Fig. V-3 are merely planes of average electrical property the actual local potentials, if they could be measured, must vary wildly between locations where there is an adsorbed ion and places where only water resides on the surface. For liquid surfaces, discussed in Section V-7C, the interface will not be smooth due to thermal waves (Section IV-3). Sweeney and co-workers applied gradient theory (see Chapter III) to model the electric double layer and interfacial tension of a hydrocarbon-aqueous electrolyte interface [27]. 

In order to calculate the distribution function must be obtained in terms of local gas properties, electric and magnetic fields, etc, by direct solution of the Boltzmann equation. One such Boltzmann equation exists for each species in the gas, resulting in the need to solve many Boltzmann equations with as many unknowns. This is not possible in practice. Instead, a number of expressions are derived, using different simplifying assumptions and with varying degrees of vaUdity. A more complete discussion can be found in Reference 34. 

FIG. 1 Schematic representation of the operation of the scanning polarization force microscope (SPFM). An electrically biased AFM tip is attracted toward the surface of any dielectric material. The polarization force depends on the local dielectric properties of the substrate. SPFM images are typically acquired with the tip scanning at a height of 100-300 A. (From Ref. 32.)... 

From comparison of the optical properties of particles deposited on the same substrate and differing by their organization (Figs. 7 and 8) it can be concluded that the appearance of the resonance peak at 3.8 eV is due to the self-organization of the particles in a hexagonal network. This can be interpreted in terms of mutual dipolar interactions between particles. The local electric field results from dipolar interactions induced by particles at a given distance from each other. Near the nanocrystals, the field consists of the ap-... 

In order to discuss the signatures of localization and delocalization and its significance for the application of nanoclusters in microelectronic devices, the following chapters will give examples about the electrical properties of nanoclusters arrays, distinguished according to their dimensionality. 

A major advantage of fluorescence as a sensing property stems from the sensitivity to the precise local environment of the intensity, i.e., quantum yield (excited state lifetime (xf), and peak wavelength (Xmax). In particular, it is the local electric field strength and direction that determine whether the fluorescence will be red or blue shifted and whether an electron acceptor will or will not quench the fluorescence. An equivalent statement, but more practical, is that these quantities depend primarily on the change in average electrostatic potential (volts) experienced by the electrons during an electronic transition (See Appendix for a brief tutorial on electric fields and potentials as pertains to electrochromism). The reason this is more practical is that even at the molecular scale, the instantaneous electric... 

However, another study concluded that the changes of the hydrogen-bond stability may be important in biological processes. For these, the influence of local electric fields created by Li+, Na+, and Mg2+ ions on the properties and reactivity of hydrogen bonds in HF and HC1 dimer has been carried out by means of ab initio self-consistent field (SCF) method [33]. A few years later, the effect of intensity and vector direction of the external electric field on activation barriers of unimole-cular reactions were studied using the semiempirical MINDO/3 method [34]. However, both semiempirical and ab initio calculations were performed to study the multiplicity change for carbene-like systems in external electric fields of different configurations (carbene and silylene) and the factor that determines the multiplicity and hence the reactivity of carbene-like structures is the nonuniformity of the field [35]. 

In general, (Eioc) 5 E, since the local electric field is averaged over the atomic sites and not over the spaces between these sites. In metals, where valence electrons are free (nonlocalized electrons), the assumption (Eioc) = E is reasonable, but for bound valence electrons (dielectrics and semiconductors) this relation needs to be known. However, for our purpose of a qualitative description of optical properties, we will still retain this assumption. 

Movements in the plane of the interface result from local variations of interfacial tension during the course of mass transfer. These variations may be produced by local variations of any quantity which affects the interfacial tension. Interfaeial motions have been ascribed to variations in interfacial concentration (H6, P6, S33), temperature (A9, P6), and electrical properties (AlO, B19). In ternary systems, variations in concentration are the major factor causing interfacial motion in partially miscible binary systems, interfacial temperature variations due to heat of solution effects are usually the cause. 

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