Subject probing structural properties

The electronic structure of fluorenes and the development of their linear and nonlinear optical structure-property relationships have been the subject of intense investigation [20-22,25,30,31]. Important parameters that determine optical properties of the molecules are the magnitude and alignment of the electronic transition dipole moments [30,31]. These parameters can be obtained from ESA and absorption anisotropy spectra [32,33] using the same pump-probe laser techniques described above (see Fig. 9). A comprehensive theoretical analysis of a two beam (piunp and probe) laser experiment was performed [34], where a general case of induced saturated absorption anisotropy was considered. From this work, measurement of the absorption anisotropy of molecules in an isotropic ensemble facilitates the determination of the angle between the So Si (pump) and Si S (probe) transitions. The excited state absorption anisotropy, rabs> is expressed as [13] ... 

Even less is known about ionomer/plasticizer interactions on a molecular level. A variety of scattering and spectroscopic techniques that can probe this level have been mentioned, but they have been applied primarily to the specific case of water in ionomers, and in particular to hjdrated perfluorinated ionomers. At the least, these studies demonstrate the powerful potential of the techniques to contribute to a more complete understanding of structure-property relationships in plasticizer/ionomer systems. For e.xample, to return to the question of the effect of nonpolar plasticizers on the ionic domains how can the decrease in the ionic transition temperature be reconciled with the apparently minimal effect on the SAXS ionomer peaks and with the ESR studies that indicate (not surprisingly) tiiat these plasticizers have essentially no influence on the local structure of the ions Is it due to their association with the hydrocai bon component of the large aggregates or clusters Or if these entities do not exist, as some researchers postulate, what is the interaction between the nonpolar plasticizer, the hydrocarbon component and the ionic domains These questions are, of course, intimately related to the understanding of ionomer microstructure even in the absence of plasticizer. The interpretation of SAXS data in particular is subject to the choice of model used. 

Although relatively understudied compared to transition metals, Pb(II) exhibits a rich coordination chemistry. Because lead is subject to relativistic effects, the electronic properties of Pb(ll) complexes are diverse and interesting. Fortunately, a wide variety of spectroscopic techniques are available to probe the properties of these compounds. In addition, detailed studies on the structures, kinetics, and thermodynamics of lead compounds provide important insights into the environmental and biological chemistry of lead(II). Through this chapter, we hope not only to have provided an overview to the chemistry of Pb(ll), but also to have corrected several misconceptions about this element ... 

Many other atom-probe analyses of different phases in different types of steels exist as steels are one of the most important materials. It is possible to investigate how the magnetic properties of alloys are correlated to the microstructures of different phases in the alloys.57,58,59 The chemical contents, growth process and structures of metallic carbides in different alloy steels have been studied with the field ion microscope and the atom-probe field ion microscope.60 61 62 63 We refer the reader to some of the original papers published on these subjects. 

The process of adsorption and interaction of probe molecules such as ammonia, carbon monoxide as well as the whole spectrum of organic reactant molecules with zeolite catalysts has been the subject of numerous experimental and computational studies. These interaction processes are studied using several computational methods involving force fields (Monte Carlo, molecular dynamics emd energy minimization) or quantum chemical methods. Another paper [1] discusses the application of force field methods for studying several problems in zeolite chemistry. Theoretical quantum chemical studies on cluster models of zeolites help us to understand the electronic and catalytic properties of zeolite catalysts. Here we present a brief summary of the application of quantum chemical methods to understand the structure and reactivity of zeolites. 

Addition reactions contain the largest synthetic potential in fullerene chemistry but they can also be used as a probe for screening the chemical properties of fullerene surfaces. Analysis of the nature of addition reactions, of geometric and electronic structures of educts and products allows one to deduce reactivity principles which are the central subject of this article. One striking conclusion is the following the fullerenes drew attention to a mostly overlooked chemistry criterion - the shape dependence of reactivity. This contribution focuses on the reactivity principles of Cgg as the most important and most intensively investigated fullerene. The addition chemistry of the higher fullerenes follows similar principles. 

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