Related Techniques

At the end of the discussion of electrochemical measurement techniques, let us, however, briefly mention that there are other techniques that are not exclusively electrochemical in natme but related to the above methods such as thermoelectric measurements and Hall-effect measurements. Both techniques are extremely helpful in combination with conductivity experiments as they then allow the splitting of the conductivities into carrier concentration and mobilities. The first method relies on the emf formed as a sheer consequence of temperatme differences (cross-effects in the thermal and chemical flux-force relations), while the second technique refers to concentration changes upon application of magnetic fields. Both techniques are particularly worked out for electroitic carriers but are more tricky and much less straightforward for ionic carriers. For more details the reader is referred to 

Both teclmiques in principle bear the potential to distinguish between p- and n-type conductors and—if applicable to ion conductors—to distinguish between interstitial and vacancy contribution provided the nature of the mobile ion is known. 

In electroitics, a well-established procedure to make statements on the sign of the electroitic carriers is establishing the appropriate junctions (cf diodes). The transformability of the semiconductor experiments to ion conductors suffers from the fact that the situation in ion conductors is more related to the situation in relaxation type semiconductors than to lifetime semiconductors note that only the latter shows the typical significant electronic effects such as in diodes or transistors. Nonetheless setting up ionic diodes and ionic transistors may be a worthwhile task for the future. (One such attempt to find out the nature of the ionic carriers (O. or V5) in PbO by diode effects, viz. by a contact to the vacancy conductive YSZ, has been reported in Ref ) 

In Part II we have seen that electrochemical cells based on solid materials are useful for a variety of electrochemical applications involving energy and information transformation. Many of these applications cannot be replaced by electronic devices and will play an increasingly important role in our future life. The same principles and cells being operative for electrochemical devices can 

The author is very much indebted to Dr. J. Fleig for helpful discussions and critically reading the manuscript. 

Over the last ten years, the STM has given birth to a whole family of scanning proximity probes [6.66]. The nature of the feedback criteria, i.e. the property being measured and used to generate the vertical detail, along with the type of sample being examined, distinguishes which SPM is used. 

Unlike the STM, the AFM does not require the sample to be conductive. The operation of the AFM, Fig. 6.7, is similar in principle to that of a profilometer in 

The cantilever position is held fixed in the AFM laser head while the sample is scanned imder the tip. See Fig. 6.7. The feedback system relies on an optical detection system that monitors the cantilever vertical deflection, dz, as the tip follows the contours of the sample surface. In the constant force mode of operation, as in the STM constant current case, dz is translated into a cor- 

A MFM can be operated in a two-pass way in much the same manner as the EFM. Like the EFM, the MFM can also be operated in two methods, with or without oscillation of the tip in the lift pass across the sample. In the former case, one can get variations in the magnetic stray fields on the surface directly. However, this method is not very sensitive to small stray fields. The second method is analogous to EFM and results in a magnetic field gradient image. 

8 and 6.9) their in-plane growth orientation likewise is growth dependent. 

Enhanced-fluidity mobile phases are prepared by dissolving a large amount of a low viscosity liquefied gas, such as carbon dioxide or fluoroform, in associated liquid 

Reversed-phase separations using superheated water have not found any major applications so far, but a wide range of low molecular mass polar compounds have been separated at modest temperatures with relatively simple and rugged instrumentation. It has potential for wider use in laboratories that wish to reduce consumption of organic solvents. In addition, superheated water should be compatible with on-column preconcentration techniques for trace analysis 

Figmre 5. Experimental setup for fast-beam laser-rf double resonance spectroscopy. (From Ref. 

Fluorescence signal versus static magnetic field applied between the optical pumping and detection regions. 

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Foord J S, Davies G J and Tsang W S 1997 Chemical Beam Epitaxy and Related Techniques (New York Wiley)... 

Dumas P, Weldon M K, Chabal Y J and Williams G P 1999 Molecules at surfaces and interfaces studied using vibrational spectroscopies and related techniques Surf. Rev. Lett. 6 225-55... 

Turbidimetry and nephelometry are two related techniques in which an incident source of radiation is elastically scattered by a suspension of colloidal particles. In turbidimetry, the detector is placed in line with the radiation source, and the... 

Stripping Voltammetry One of the most important quantitative voltammetric techniques is stripping voltammetry, which is composed of three related techniques anodic, cathodic, and adsorptive stripping voltammetry. Since anodic strip-... 

X-ray Photoelectron Spectroscopy. X-ray photoelectron spectroscopy (xps) and Auger electron spectroscopy (aes) are related techniques (19) that are initiated with the same fundamental event, the stimulated ejection of an electron from a surface. The fundamental aspects of these techniques will be discussed separately, but since the instmmental needs required to perform such methods are similar, xps and aes instmmentation will be discussed together. 

A related technique is based on the same principles, only the trap population is measured by means of esr spectrometry (see Magnetic spin resonance) (50). 

A closely related technique useful for localized gas concentrations and leaks is photoacoustic detection and ranging (padar) (90). A laser pulse tuned to an absorption line generates an acoustic signal that is detected by a paraboHc microphone. A range resolution of 1 cm out to 100 m is feasible. 

Frequency Estimation There are two primary sources for estimates of incident frequencies. These are historical records and the apphcation of fault tree analysis and related techniques, and they are not necessarily applied independently. Specific historical data can sometimes be usehiUy applied as a check on frequency estimates of various subevents of a fault tree, for example. 

In general, two related techniques may be used principal component analysis (PCA) and principal coordinate analysis (PCoorA). Both methods start from the n X m data matrix M, which holds the m coordinates defining n conformations in an m-dimensional space. That is, each matrix element Mg is equal to q, the jth coordinate of the /th conformation. From this starting point PCA and PCoorA follow different routes. 

J. I. Goldstein, Dale E. Newbury, P. Echlin, D. C. Joy, C. Fiori, and E. Lif-shin. Scanning Microscopy and X-Ray Microanalysis. Plenum Press, New York, 1981. An excellent and widely ranging introductory textbook on scanning microscopy and related techniques. Some biological applications are also discussed. 

As is common to most techniques, XPD and AED have spawned related techniques that are too specialized to present in detail here, but the reader should be at least aware of some of the more interesting ones, which show future possibilities. 

A somewhat related technique is that of laser ionization mass spectrometry (LIMS), also known as LIMA and LAMMA, where a single pulsed laser beam ablates material and simultaneously causes some ionization, analogous to samples beyond the outer surface and therefore is more of a bulk analysis technique it also has severe quantiBaction problems, often even more extreme than for SIMS. 

In the Encyclopedia, 50 brief articles (each 10—18 pages in length) are presented in a standard format designed for ease of reader access, with straightforward technique descriptions and examples of their practical use. In addition to the articles, there are one-page summaries for every technique, introductory summaries to groupings of related techniques, a complete glossary of acronyms, and a tabular comparison of the major features of all 50 techniques. 

The articles follow a standard format for each technique A clear description of the technique, the range of information it provides, the range of materials to which it is applicable, a few typical examples, and some comparison to other related techniques. Each technique has a quick reference, one-page summary in Chapter 1, consisting of a descriptive paragraph and a tabular summary. 

The procedures of measuring changes in some physical or mechanical property as a sample is heated, or alternatively as it is held at constant temperature, constitute the family of thermoanalytical methods of characterisation. A partial list of these procedures is differential thermal analysis, differential scanning calorimetry, dilatometry, thermogravimetry. A detailed overview of these and several related techniques is by Gallagher (1992). 

The thixocasting mentioned above exploits dendritic solidification of alloys a semi-solidified alloy is forged under pressure into a die the dendrites are broken up into small fragments and a sound (pore-free) product is generated at a relatively low temperature, prolonging die-life. The array of related techniques of which this is one was introduced by Flemings and Mehrabian in 1971 and Flemings (1991) has recently reviewed them in depth. 

However, in the case of a root cause analysis system, a much more comprehensive evaluation of the structure of the accident is required. This is necessary to unravel the often complex chain of events and contributing causes that led to the accident occurring. A number of techniques are available to describe complex accidents. Some of these, such as STEP (Sequential Timed Event Plotting) involve the use of charting methods to track the ways in which process and human events combine to give rise to accidents. CCPS (1992d) describes many of these techniques. A case study involving a hydrocarbon leak is used to illustrate the STEP technique in Chapter 7 of this book. The STEP method and related techniques will be described in Section 6.8.3. 

Electrochemical noise A variety of related techniques are now available to monitor localized corrosion. No external polarization of the corroding metal is required, but the electrical noise on the corrosion potential of the metal is monitored and analyzed. Signatures characteristic of pit initiation, crevice corrosion and some forms of stress corrosion cracking is obtained. 

A diagnostic method using fluorescence labeled DNA probes to detect and quantify the number complementary chromosomal sequences on a cellular resolution. A related technique that also allows assessment of gene amplifications, but without precise quantification of copy numbers is the chromogenic in situ hybridization (CISH). Here, instead of a fluorescent dye an enzyme that can generate a colored precipitate in the tissue samples is coupled to the DNA probe. 

Fast atom bombardment mass spectrometry and related techniques. J. M. Miller, Adv. Inorg. Chem. Radiochem., 1984,28,1 (118). 

A related technique, reverse-pulse voltammetry, has a pulse sequence that is a mirror image of that of normal-pulse voltammetry (5). hi this case, the initial potential is on the plateau of the wave (i.e., where reduction occurs), and a series of positive-going pulses of decreasing amplitude is applied. 

A related technique involves incorporation of monofunctional poly(etliylene oxide) chains as nonionic, internal emulsifier groups. Even PMDI can be dispersed in water using this nonionic method (Scheme 4.24). High-molecular-weight (ca. 2000 g/m) monols are usually used which act as chain terminators and long, hydrophilic tails which function as an emulsifying agent. 

The heating curve of a substance, like that in Fig. 6.26, shows how its temperature changes as heat is supplied at a constant rate, usually at constant pressure. How are these curves produced Simple laboratory heaters can be used to obtain a crude estimate of a heating curve. However, for accuracy, one of two related techniques is normally used. 

Because the scent of a flower may be due to hundreds of different compounds, it is difficult for perfume manufacturers to duplicate floral scents. Establishing the identities and relative amounts of the components of a fragrance was actually impossible until the development of chromatography. Related techniques are used in forensic laboratories to match samples of fluids, by food manufacturers to test product quality, and to search for evidence of life on other planets. All these techniques depend on subtle differences in intermolecular forces to separate compounds. 

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