Chemical composition distribution, direct characterization

Size-resolved chemical information is much more difficult to obtain. The many applications of the differential mobility analyzer in measuring properties of size-classified particles are important tools for the characterization of aerosol systems, but the approaches demonstrated to date yield limited data. Vapor pressures, surface tension, and optical absorption have been measured on mobility-classified aerosols. Direct measurements of the distribution of chemical composition with particle size are needed. Elemental... 

Microscopic techniques are attractive for suspension characterization because they are capable of directly determining the size distribution of the suspended phase as well as chemical compositional infor-... 

Synthetic copolymers are always poly disperse, i.e., they consist of a large number of chemically similar species with different molar masses and different chemical compositions. Owing to this polydispersity, characterization of copolymers does usually not provide the number of individual molecules or their mole fraction, mass fraction, etc. but requires the use of continuous distribution functions or their averages. Continuous thermodynamics, developed by Ratzsch and Kehlen [1], can be directly applied to the calculation of thermodynamic properties, including phase equilibria, because this theoretical framework is based completely on continuous distribution functions, which include all the information about these functions and allow an exact mathematical treatment of all related thermodynamic properties. Continuous thermodynamics have been used for calculation of phase equilibria of systems containing two-dimensional distributed copolymers [1-8]. The purpose of this contribution is the application of continuous thermodynamics to copolymer fractionation according to the chemical composition and molecular weight. 

These studies demonstrate that the superficial composition of the perovskite is very important and surface content/distribution of the cations may influence the oxidation process. In this respect, the use of low-energy ion scattering as a recent advanced surface characterization technique allowed the direct analysis of the outermost surface layer of such materials with an escape depth of 0.3 nm [17]. Results collected from these characterizations show that the chemical nature of the cations is the factor determining the preferential surface segregation of one of the components [18]. 

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