Characterisation techniques infrared spectroscopy

Dealuminated M-Y zeolites (Si/Al = 4.22 M NH4, Li, Na, K, Cs) were prepared using the dealumination method developed by Skeels and Breck and the conventional ion exchange technique. These materials were characterised by infrared spectroscopy (IR) with and without pyridine adsorption, temperature-programmed desorption (t.p.d.) of ammonia. X-ray difiracto-metry (XRD) and differential thermoanalysis (DTA). They were used for encapsulation of Mo(CO)5. Subsequent decarbonylation and ammonia decomposition was monitored by mass spectrometry (MS) as a function of temperature. The oxidation numbers of entrapped molybdenum as well as the ability for ammonia decomposition were correlated to the overall acidity of the materials. It was found that the oxidation number decreased with the overall acidity (density and/or strength of Bronsted and Lewis acidity). Reduced acidity facilitated ammonia decomposition. 

Standardisation of EPDM characterisation tests (molecular composition, stabiliser and oil content) for QC and specification purposes was reported [64,65]. Infrared spectroscopy (rather than HPLC or photometry) is recommended for the determination of the stabiliser content (hindered phenol type) of EP(D)M [65]. Determination of the oil content of oil-extended EPDM is best carried out by Soxhlet extraction using MEK as a solvent [66], A round robin test was reported that evaluated the various techniques currently used in the investigation of unknown rubber compounds (passenger tyre tread stock formulations) [67]. 

Chemical characterisation of F uptake in archaeological bone has already been developed in the 19th century [1,2] and is now well established [60], However, relatively few studies use a combined multianalytical approach using trace elemental and microstructure analytical techniques (PIXE/PIGE, TEM-EDX) for evidencing modifications on different microscopic and nanoscopic levels (Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), SEM, TEM) and enabling an objective evaluation of the F uptake mechanisms [32-34,51],... 

IR spectroscopy can be used to characterise not only different rubbers, but also to understand the structural changes due to the chemical modification of the rubbers. The chemical methods normally used to modify rubbers include hydrogenation, halogenation, hydrosilylation, phosphonylation and sulfonation. The effects of oxidation, weathering and radiation on the polymer structure can be studied with the help of infrared spectroscopy. Formation of ionic polymers and ionomeric polyblends behaving as thermoplastic elastomers can be followed by this method. Infrared spectroscopy in conjunction with other techniques is an important tool to characterise polymeric materials. 

The problem with sulfide catalysts (hydrotreatment) is to determine the active centres, which represent only part of their total surface area. Chemisorption of O2, CO and NO is used, and some attempts concern NIL, pyridine and thiophene. Static volumetric methods or dynamic methods (pulse or frontal mode) may be used, but the techniques do not seem yet reliable, due to the possible modification (oxidation) of the surface or subsurface regions by O2 or NO probe molecules or the kinetics of adsorption. CO might be more promising. Infrared spectroscopy, especially FTIR seems necessary to characterise co-ordinativcly unsaturated sites, which are essential for catalytic activity. CO and NO can also be used to identify the chemical nature of sites (sulfided, partially reduced or reduced sites). For such... 

Physical methods for size determination are mainly related to the use of X-ray based diffraction, scattering and absorption techniques, microscopy, and magnetic measurements. Physical and chemical methods may be combined, for example, in the use of infrared spectroscopy coupled to the use of probe molecules such as CO to determine the fraction of exposed metal atoms. However, as Chp 3 has already dealt with characterisation of supported metal systems by X-ray absorption and infrared spectroscopies in some detail, they will not be included here. 

The reactions can be quantified even before visible damage occurs by analysing the components dissolved in the solution (preferably by ICP-AES) or by characterising the altered glass surface (with surface-sensitive techniques such as X-ray photoelectron spectroscopy (XPS), and Infrared-spectroscopy (IR)). 

Study of the solubility and solid phases encountered in the Zr02-H3P04-H20 system over the temperature range of 20 to 100°C. Techniques used include differential thermal calorimetry, thermogravimetric analysis, infrared spectroscopy and X-ray diffraction analysis. The paper discusses briefly the changes occurring in the solid phases over the temperature shift, but is poor in characterising the solution composition since the concentrations of the constituent ions were below the detectable concentrations. No chemical thermodynamics data are detailed in the paper. 

Infrared spectroscopy has also been combined with other established analytical techniques, e.g. thermogravimetric analysis (TGA). The latter is a technique which involves measuring the change of the mass of a sample when it is heated. While TGA can provide quantitative information about a decomposition process, it is unable to identify the decomposition products. However, TGA and infrared spectroscopy have been combined to provide a complete qualitative and quantitative characterisation of various thermal decomposition processes. 

A multitude of characterisation techniques were used to evidence the occurrence of the different reaction sequences Fourier transform infrared spectroscopy (FTIRS), solid NMR spectroscopy (C-PMAS) (Figure 17.17), contact angle measurements, and X-ray photoelectron spectroscopy (XPS) (Figure 17.18). 

Gar side and Wyeth [30] have used Fourier transform infrared spectroscopy to characterise cellulose fibres such as jute, sisal, and cotton. The technique has also been used to determine... 

The application of AFM and other techniques has been discussed in general terms by several workers [350-353]. Other complementary techniques covered in these papers include FT-IR spectroscopy, Raman spectroscopy, NMR spectroscopy, surface analysis by spectroscopy, GC-MS, scanning tunnelling microscopy, electron crystallography, X-ray studies using synchrotron radiation, neutron scattering techniques, mixed crystal infrared spectroscopy, SIMS, and XPS. Applications of atomic force spectroscopy to the characterisation of the following polymers have been reported polythiophene [354], nitrile rubbers [355], perfluoro copolymers of cyclic polyisocyanurates of hexamethylene diisocyanate and isophorone diisocyanate [356], perfluorosulfonate [357], vinyl polymers... 

Chemical type, ionic character, viscosity, average molar mass and molar mass distribution are properties of a polymer that may be characterised. Determination of chemical type may be accomplished using a variety of techniques such as infrared spectroscopy, GC-pyrolysis, NMR and elemental analysis techniques. 

Advanced analytical techniques as well as special accessories evolve from custom-made laboratory units into commercially available devices. Toward a more comprehensive characterisation of swelling and switching layer systems, different analytical techniques are combined in a single set-up. Examples closely related to the topic of this chapter are a unit for simultaneous measurements by QCM-D and ellipsometry (see application notes at www.q-sense.com) as well as a combined set-up for microslit electrokinetic measurements and reflectometric interference spectroscopy or Fourier transform infrared spectroscopy, respectively (see www.zetascience.info). 

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