Characterization method

After the process of synthesis, a thorough characterization of the obtained materials is necessary. It is almost impossible to understand the properties of a material and, consequently, its proper application, if we do not understand its composition, structure, and morphology. A task of fundamental importance in the physical chemistry of materials, as in all material sciences, is characterization.  

Raman spectroscopy has been applied to determine the stiffness (modulus) of CNCs and stress-transfer in CNCs-reinforced composites or biocomposites where reinforcing phase is too small to be characterized by using standard mechanical techniques. This technique involves the measurement of deformation (a shift in the carbonyl (C-O) mode of the cellulose chain) [96], Originally these shifts of Raman bands were reported for single crystals of polydiacetylene [97] and composites [98] followed by shifts reported for stressed regenerated cellulose fibers [99]. The Raman bands shift is the indication of molecular deformation and determine the extent of stress-transfer between reinforcing CNCs and matrix. The intensity of Raman band measures the orientation distribution of the nanocrystals in composites [96]. Recently, some researchers measured the stress-transfer behavior in microfibrillated cellulose-reinforced polylactic acid and cellulose nanowhiskers-reinforced epoxy-resin composites [96,100]. 

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In this chapter we review some of the most important developments in recent years in connection with the use of optical teclmiques for the characterization of surfaces. We start with an overview of the different approaches available to tire use of IR spectroscopy. Next, we briefly introduce some new optical characterization methods that rely on the use of lasers, including nonlinear spectroscopies. The following section addresses the use of x-rays for diffraction studies aimed at structural detenninations. Lastly, passing reference is made to other optical teclmiques such as ellipsometry and NMR, and to spectroscopies that only partly depend on photons. 

The final technique addressed in this chapter is the measurement of the surface work function, the energy required to remove an electron from a solid. This is one of the oldest surface characterization methods, and certainly the oldest carried out in vacuo since it was first measured by Millikan using the photoelectric effect [4]. The observation of this effect led to the proposal of the Einstein equation ... 

Fliemenz P C and Ra]agopalan R 1997 Principles of Colloid and Surface Chemistry 3rd edn (New York Marcel Dekker) General textbook on colloid and surface science, including details about characterization methods Flunter R J 1987 and 1989 Foundations of Colloid Science vols I and II (Oxford Clarendon Press)... 

Analysis. Excellent reviews of phosphate analysis are available (28). SoHds characterization methods such as x-ray powder diffraction (xrd) and thermal gravimetric analysis (tga) are used for the identification of individual crystalline phosphates, either alone or in mixtures. These techniques, along with elemental analysis and phosphate species deterrnination, are used to identify unknown phosphates and their mixtures. Particle size analysis, surface area, microscopy, and other standard soHds characterizations are useful in relating soHds properties to performance. SoHd-state nmr is used with increasing frequency. 

Modulation Spectroscopy has proven to be an important characterization method for semiconductors and semiconductor microstructures. The rich spectra contain a wealth of information about relevant materials, surfaces and interfrces, as well as device characteristics. In general, the apparatus is relatively simple, compact (except EBER), inexpensive (except EBER), and easy to use. One of the main advantages of Modulation Spectroscopy is its ability to perform relevant measurements at room... 

Modem Characterization Methods of Surfactant Systems, edited by Bernard P. Binks... 

Surface Characterization Methods Principles, Techniques, and Applications, edited by Andrew J. Milling... 

It is quite reasonable to expect the bimolecular two-stage mechanism Sj Ar ) to predominate in most aromatic nucleophilic substitutions of activated substrates. However, only in rare instances is there adequate evidence to rule out the simultaneous occurrence or predominance of other mechanisms. The true significance of the alternative mechanisms in azines needs to be determined by trapping the intermediates or by applying modem separation and characterization methods to the identification of at least the major portion of the products, especially in kinetic studies. 

Other characterization methods are usually used to detect the changes in physical properties, which usually result from the changes in the morphology and structures of the substrates due to grafting. 

Polyesters are not different from other polymers, and any of the characterization methods commonly used in polymer science can obviously be applied to polyesters and provide information on their structure and properties. In this section, some data specific to polyesters—solubility information, COOH and OH endgroup titration, and infrared (IR) and NMR spectra assignments—are briefly summarized. Most of these data originate from the authors laboratory. References are provided on some particular points only. 

The most widely used molecular weight characterization method has been GPC, which separates compounds based on hydrodynamic volume. State-of-the-art GPC instruments are equipped with a concentration detector (e.g., differential refractometer, UV, and/or IR) in combination with viscosity or light scattering. A viscosity detector provides in-line solution viscosity data at each elution volume, which in combination with a concentration measurement can be converted to specific viscosity. Since the polymer concentration at each elution volume is quite dilute, the specific viscosity is considered a reasonable approximation for the dilute solution s intrinsic viscosity. The plot of log[r]]M versus elution volume (where [) ] is the intrinsic viscosity) provides a universal calibration curve from which absolute molecular weights of a variety of polymers can be obtained. Unfortunately, many reported analyses for phenolic oligomers and resins are simply based on polystyrene standards and only provide relative molecular weights instead of absolute numbers. 

Due to diffraction effects of micron-sized mirrors in a regular array, commonly used techniques for surface characterization based on interferometry are inefficient. To overcome the diffraction effects we have developed a novel surface characterization method with an incoherent light source, based on the Foucault s knife-edge test (Zamkotsian and Dohlen, 1999). Since Leon Foucault introduced the knife-edge test in the last century (Foucault, 1859), it has been widely used for testing optical surfaces (see Ch. 3). The test offers a simple way of obtaining easily understandable, qualitative information of the surface shape. 

Following upon the success of the ACOL series, which by its very name is predominately concerned with Analytical Chemistry, the Analytical Techniques in the Sciences (AnTs) series of open learning texts has now been introduced with the aim of providing a broader coverage of the many areas of science in which analytical techniques and methods are now increasingly applied. With this in mind, the AnTs series of texts seeks to provide a range of books which will cover not only the actual techniques themselves, but also those scientific disciplines which have a necessary requirement for analytical characterization methods. 

Special Characterization Methods for Silica-Rubber Coupling.805... 

The nanometer level of characterization is necessary for nanochemistry. We have learned from the history of once-new disciplines such as polymer science that progress in synthesis (production method) and in physical and chemical characterization methods are essential to establish a new chemistry. They should be made simultaneously by exchanging developments in the two areas. Surface forces measurement is certainly unique and powerful and will make a great contribution to nanochemistry, especially as a technique for the characterization of solid-liquid interfaces, though its potential has not yet been fully exploited. Another important application of measurement in nanochemistry should be the characterization of liquids confined in a nanometer-level gap between two solid surfaces, for which this review cites only Refs. 42-43. 

The goal of this work was to prepare and characterize PtRu/MgO catalysts from cluster A which contained Pt-Ru bonds and compare with that prepared from a mixed solution of Pt(acac)2 and Ru(acac)3. The characterization methods included IR and EXAFS spectroscopy. Ethylene hydrogenation was used to test the catalytic activity of both PtRu/MgO catalysts. 

The different growth modes discussed above have been exemplified also from structural studies. Froment and Lincot [247] used structural characterization methods, such as TEM and HRTEM, to determine the formation mechanisms and habits of chemically deposited CdS, ZnS, and CdSe thin film at the atomic level. These authors formulated reaction schemes for the different deposition mechanisms and considered that these should be distinguished to (a) atom-by-atom process, providing autoregulation in normal systems (b) aggregation of colloids (precipitation) ... 

Characterization methods. The 100 kV Vacuum Generator HB-5 STEM was used to mlcroanalyze samples. The HB-5 has a KEVEX SI(LI) energy dispersive X-ray spectrometer (EDS) and micro area electron diffraction (MAED) capabilities In conjunction with simultaneous bright and dark field Imaging capabilities. A more detailed explanation of the Instrumental operation can be obtained In a publication by C. Lyman(12). 

The MWBD method, when coupled with high speed SEC techni-gues, is more rapid for long chain branching measurements than NMR. In addition, the branching distribution information that it provides, once epsilon has been determined, can not be obtained by other branching characterization methods unless the polymer is fractionated. 

Principally purification and characterization methods of monometallic nanoparticles are directly applied to those of bimetallic nanoparticles. Purification of metal nanoparticles dispersed in solution is not so easy. So, in classical colloid chemistry, contamination is carefully avoided. For example, people used pure water, distilled three times, and glass vessels, cleaned by steam, for preparation of colloidal dispersions. In addition, the reagents which could not byproduce contaminates were used for the preparation. Recently, however, various kinds of reagents were used for the reaction and protection. Thus, the special purification is often required especially when the nanoparticles are prepared by chemical methods. 

After purification, the bimetallic nanoparticles are offered to characterization. The characterization techniques were well reviewed previously in literatures [1,2]. In this section, we highlight recent reports on the characterization methods of bimetallic nanoparticles after presenting some previous researches again. 

In this paper we have endeavored to present a review of some characterization methods of metal nanoclusters, focusing, among the extremely vast array of methods and techniques, on two of them, XRD and TEM, on which we have direct experience, and emphasizing also some recent developments, like the radial distribution function in XRD and EH in TEM. 

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