Technique limitations

Borehole logging and mapping, geophysical techniques (limited)... 

There should be no perceptible drop in pressure as shown by the test gauge, although a small leakage rate is defined which allows for testing technique limitations. 

The STEM Is Ideally suited for the characterization of these materials, because one Is normally measuring high atomic number elements In low atomic number metal oxide matrices, thus facilitating favorable contrast effects for observation of dispersed metal crystallites due to diffraction and elastic scattering of electrons as a function of Z number. The ability to observe and measure areas 2 nm In size In real time makes analysis of many metal particles relatively rapid and convenient. As with all techniques, limitations are encountered. Information such as metal surface areas, oxidation states of elements, chemical reactivity, etc., are often desired. Consequently, additional Input from other characterization techniques should be sought to complement the STEM data. 

Provides much more information about molecular structure than any other technique. Limitations... 

Method Process Particles/ ray measured Depth resolution Lateral resolution Imaging possibility Detection limits Strengths of technique Limitations of technique... 

Fig. 9.5. Raman chemical images of tablet formulations with different API form compositions to demonstrate technique limit of detection of 0.01% w/w for form D...

Analyte Detection technique Limit of detection Reference... 

In modem NMR, in order to obtain data on through-bond, scalar connectivities or through-space, dipolar connectivities between individual spins, double or multiple irradiation experiments are used. These rely on selective irradiation of a particular resonance line with a radio frequency field and observation of the resulting effects in the rest of the spectrum. With 2D ESR techniques as well as with 2D NMR techniques, limitations of one-dimentional methods connected with overlapping resonance have been overcome (Fig. 1.7). 

URANIUM-SERIES DATING OF SPELEOTHEMS CURRENT TECHNIQUES, LIMITS, APPLICATIONS... 

The major advantages of the PIMS technique is its flexibility (it is able to monitor a large number of different hydrocarbon radicals and the products of the reactions such as methyl radicals or propene), and sensitivity. The low concentrations of radicals ensure the decomposition reaction is isolated for study. Unfortunately there are two significant drawbacks to the technique. The use of mass spectrometric detection and a flow system limits the pressure of the experimental technique. Neither of the two reactions shown in Fig. 2.16 is in the high pressure limit and therefore modelling and extrapolation are required to obtain this parameter. Secondly, the restrictions of the maximum first-order rate coefficient which can be studied with the technique limit the temperature range of the studies to relatively narrow regions. 

Of all the proposed leach-resistant formulations, only the amino-resin systems are used commercially. The high costs of many of the other proposed techniques limit their acceptability. 

Dimethylphenylphosphine-borane has been prepared in good yield by the displacement of trimethylamine by the less volatile dimethyl-phenylphosphine from trimethylamine-borane.1 This method could be extended to the syntheses of other phosphine-boranes, but it involves the use of expensive trimethylamine-borane. The direct combination2 of diborane with substituted phosphines could give good yields of pure phosphine-boranes, but the required use of vacuum-line techniques limits its utility to small-scale preparations. For the bulk synthesis of phosphine-boranes, the method reported by Nainan and Ryschkewitsch3 has been found to be most suitable, and we have now extended this method to the syntheses of dimethylphenylphosphine-borane and methyldiphenylphosphine-borane. 

Although some optical techniques, such as soft X-ray absorption and optical reflectance measurements, provide comparative information about solids with higher energy resolution, EELS enjoys several unique advantages over optical spectroscopies. First of all, unlike optical reflectance measurements which are sensitive to the surface condition of the sample, the transmitted EELS represents the bulk properties of the material. Secondly, EELS spectra can be measured with q along specific controllable directions and thus, can be used to study the dispersion of plasmons, excitons, and other excitations [8.1-8.5]. Such experiments offer both dynamics as well as symmetry information about the electronic excitations in solids. In addition, the capability to probe the electronic structure at finite momentum-transfer also allows one to investigate the excited monopole or quadrupole transitions, which cannot be directly observed by conventional optical techniques limited by the dipole selection rule. 

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