Results and Discussion of Selected Examples

The sensitivity achieved (LOD) is not normally presented. It is recognized that different laboratories determine dissimilar values for this parameter and even within a laboratory the repeatability of the LOD is low. Most often, the lowest validated concentration gives an impression about the lowest levels that can be analyzed generally with acceptable results. A measure of selectivity is the intensity of blank results. This intensity is discussed by the participants of inter-laboratory validation studies. However, results are not reported and limits are not defined by CEN TC 275. The results of method validations of the several multi-residue/multi-matrix methods are not reported in the same way, but newer methods with limited scope generate analogous tables with validation results (as an example, see Table 7). 

All the above species have been detected in various quantities at oxide surfaces. The discussion of this example serves mainly to show that catalytic reactions at oxide surfaces are very complex. This is a mixed blessing from the sensing point of view. It provides a broad spectrum of reactions that could be used. On the other hand, it can lead to great variation in the results obtained with only slightly different sensors. Another drawback of such a complex and diverse mechanism is the relatively slow time response which, in most cases, is limited by the rates of the chemical reactions (Fig. 8.10). Naturally, one tendency of the current research in this field is to increase the selectivity of the surface reactions by introducing additional catalytic control, for example, by incorporation of catalytic metals, metal clusters, and other surface modifiers. 

In Secs. 5-10 we present a series of selected examples of the use of the external reflectance technique to investigate some electrochemical systems of interest. Results from the electrochemical literature on the adsorption of hydrogen, carbon monoxide and alcohols are discussed and compared with the data from UHV measurements (Secs. 5-7). 

Solutions of these two problems are to some degree independent, and their combination results in different adsorption models. Detailed discussion of all possible combinations is not intended. This chapter is limited to presentation of selected examples, and to discussion, how different (often contradictory) assumptions affect the resultant model curves. 

The growing interest manifested by synthetic chemists towards the use of the asymmetric dihydroxylation of olefins has resulted in so many varied apphca-tions that it is beyond the scope of this limited review to enumerate them all. Throughout this concise review, the specificities of the catalytic AD of alkenes have been discussed and the salient features of the almost limitless transformations of the resulting chiral diols have been illustrated through the use of selected examples. Whilst the AD of olefins is now considered as one of the most important tools in asymmetric synthesis, let us not forget that the enantioselectiv-ity displayed by the asymmetric dihydroxylation process can depend upon subtle steric, electronic or conformational effects that are far less pronounced in other asymmetric catalytic reactions. Such is the case in our last example [141], featuring an elegant approach towards vitamin E by Tietze and coworkers... 

Based on the findings, we exclude further discussion on SolidWorks and Wildfire due to their poor performance in the first evaluation round. In the following we discuss results of Ceomagic and Rapidfbrm for selected examples to consolidate our conclusions. 

The aim of this talk is to review the results obtained in the studies of inner-shell ionization and decay by means of photoelectron (PES) and Auger electron spectrometry (AES). Since the scope of such a talk would be much too broad I will consider AES only in connection with photon or electron impact ionization. AES associated with ion-atom collisions, important for studies of multi-ionized atoms, will not be discussed. The angular anisotropy of photo- and Auger electrons will also not be treated in spite of the fact that for inner-shells the B-para-meter may depend sensitively on the structure and the dynamics of the atom, in particular for heavier atoms (e.g. Xe(4d) > ). Therefore my talk will be more selective than exhaustive. By means of selected examples of inner-shell photo and Auger electron spectra I will demonstrate the sort of information one can obtain for atoms. The main emphasis will be laid on effects caused by the electron correlation. Reviews on parts of this subject have been given earlier by Siegbahn et al. Krause >, Mehlhorn , Wendin and most recently by Siegbahn and Karlsson ... 

---