Electric field analysis

Ion mobility spectrometry (IMS), which has the ability to separate ionic species at atmospheric pressure, is another technique that is useful for detect and characterising organic vapours in air [97]. This involves the ionisation of molecules and their subsequent drift through an electric field. Analysis is based on analyte separations resulting from ionic mobilities rather than ionic masses. A major advantage of operation at atmospheric pressure is that it is possible to have smaller analytical units, lower power requirements, lighter weight and easier use. 

Jones, R.T., Williams, T.J., and Abu Sharkh, S., Assessment of industrial electrostatic hazards using finite element electric field analysis, J. Electrostatics, 40 41, 449 154, 1997. 

X. Wang, X-B. Wang, F. F. Becker and P. R. C. Gascoyne, A theoretical method of electric field analysis for dielectrophoretic electrode arrays using Green s theorem, J. Phys. D Appl. Phys., 29, 1649-1660 (1996). 

Even slower dissociation rates can be measured by storing ions in an ion trap such as a pulsed ion cyclotron resonance (ICR) cavity (So and Dunbar, 1988) or a quadru-pole ion trap (March et al., 1992), both of which can trap the ions up to several seconds. In the ICR, ions are trapped by a combination of DC electric and magnetic fields, while in the quadrupole trap, they are stored by a combination of RF and DC electric fields. Analysis of either the depleted parent ions or the newly formed product ions is carried out by pulsed extraction of mass selected ions. Thus, the timing with respect to the photodissociation pulse is achieved by delayed ion extraction. The long time limit in this experiment is determined not by the trapping time of the instrument, but by the IR fluorescence rate of ions which is typically 10 to 10 sec > (Dunbar, 1990 Dunbar et al., 1987). 

Harrick [156] and Hansen [99] gained insight into the physics of the ATR spec-tram of a layered stracture and derived formnlas for the penetration depth and the contribntion of the surface layer to the net absorption. Electric field analysis has also been employed to explain the phenomena of SEWs [132, 157, 158] and the excitation of surface polaritons [159, 160], In addition, EEA has been shown to be a basis for an approximate estimation of the molecular orientation (Section 3.11). However, as will be shown below, the MSEEs cannot be used to compare the spectral contrast for the same film in different optical systems. 

Hayase M, Hatsuzawa T, Fukuizumi A (2002) Electric field analysis in a dilute solution for the vibrating electrode technique. J Electroanal Chem 537 173-181... 

Zheng Y, Zeng Y (2014) Electric field analysis of spinneret design for multihole electrospinning system. J Mater Sci 49 1964-1972... 

Wang X, Lin T, Wang X (2014) 3D electric field analysis of needleless electrospinning from a ring coil. J Ind Text 44 463-476... 

S. Matsuno, Y. Iso, H. Uchida, I. Oono, T. Fukui and T. Ooba. CFD modeling coupled with electric field analysis for Joule-heated glass melters. J. Power Energy Syst. 2 (1), 2008, 447. 

The chemical, stmctural, and electronic characteristics of surfaces and interfaces are usually different from those of the bulkphase(s). Thus, methods to be used for the analysis of surfaces must be selective in response to the surface or interfacial region relative to the bulk. Surfaces and interfaces are most commonly explored using techniques based on the interaction of photons, electrons, or ions with the surface or using a force such as electric field or van der Waals attraction. These excitations generate a response involving the production of photons, electrons, ions or the alteration of a force that is then sensed in the analysis. 

The theory and appHcation of SF BDV and COV have been studied in both uniform and nonuniform electric fields (37). The ionization potentials of SFg and electron attachment coefficients are the basis for one set of correlation equations. A critical field exists at 89 kV/ (cmkPa) above which coronas can appear. Relative field uniformity is characterized in terms of electrode radii of curvature. Peak voltages up to 100 kV can be sustained. A second BDV analysis (38) also uses electrode radii of curvature in rod-plane data at 60 Hz, and can be used to correlate results up to 150 kV. With d-c voltages (39), a similarity rule can be used to treat BDV in fields up to 500 kV/cm at pressures of 101—709 kPa (1—7 atm). It relates field strength, SF pressure, and electrode radii to coaxial electrodes having 2.5-cm gaps. At elevated pressures and large electrode areas, a faH-off from this rule appears. The BDV properties ofHquid SF are described in thehterature (40—41). 

In plasma chromatography, molecular ions of the heavy organic material to be analy2ed are produced in an ionizer and pass by means of a shutter electrode into a drift region. The velocity of drift through an inert gas at approximately 101 kPa (1 atm) under the influence of an appHed electric field depends on the molecular weight of the sample. The various sonic species are separated and collected every few milliseconds on an electrode. The technique has been employed for studying upper atmosphere ion molecule reactions and for chemical analysis (100). 

Modes of Operation There is a close analogy between sedimentation of particles or macromolecules in a gravitational field and their elec trophoretic movement in an electric field. Both types of separation have proved valuable not only for analysis of colloids but also for preparative work, at least in the laboratoiy. Electrophoresis is applicable also for separating mixtures of simple cations or anions in certain cases in which other separating methods are ineffectual. 

As mentioned above, the interpretation of CL cannot be unified under a simple law, and one of the fundamental difficulties involved in luminescence analysis is the lack of information on the competing nonradiative processes present in the material. In addition, the influence of defects, the surface, and various external perturbations (such as temperature, electric field, and stress) have to be taken into account in quantitative CL analysis. All these make the quantification of CL intensities difficult. Correlations between dopant concentrations and such band-shape parameters as the peak energy and the half-width of the CL emission currently are more reliable as means for the quantitative analysis of the carrier concentration. 

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