Reflectance IR spectroscopy

In infra-red attenuated total reflection spectroscopy (IR-ATR) and grazing incidence reflection IR spectroscopy (IR-GIR) the evanescent wave of a totally... 

The first two advantages listed above allow an optical method like transmission or reflection IR spectroscopy to be used for studies which would be impossible for a widely used competitive technique, electron energy loss spectroscopy (EELS). EELS must... 

Kubanek, P., Busch, O., Thomson, S. et al. (2004) Imaging reflection IR spectroscopy as a tool to achieve higher integration for high-throughput experimentation in catalysis research. J. Comb. Chem., 6, 420. 

Specular reflection IR spectroscopy has been used by Cole and coworkers to study the orientation and structure in PET films [36,37]. It has allowed characterizing directly very highly absorbing bands in thick samples, in particular the carbonyl band that can show saturation in transmission spectra for thickness as low as 2 pm. The orientation of different conformers could be determined independently. Specular reflection is normally limited to uniaxial samples because the near-normal incident light does not allow measuring Ay. However, it was shown that the orientation parameter along the ND can be indirectly determined for PET by using the ratio of specifically selected bands [38]. This approach was applied to the study of biaxially oriented PET bottles [39]. 

Antiblock additives can be seen on the surface of films using optical microscopy or SEM. Identification can normally be achieved with internal reflection IR spectroscopy (e.g., with a germanium crystal to minimise sampling depth) or using an X-ray attachment with the electron microscope. 

Vigano, C., Manciu, L., Buyse, F., Goormaghtigh, E., Ruysschaert, J.M. (2000). Attenuated total reflection IR spectroscopy as a tool to investigate the structure, orientation and tertiary structure changes in peptides and membrane proteins. Biopolymers, 55(5), 373-380. 

Attenuated total reflection IR spectroscopy can be used to investigate model as well as powder catalysts. 

Attenuated total reflection IR spectroscopy is an established tool in a variety of research fields. The theory is well documented, but the application of this method for investigations of catalysts under working conditions has been explored only... 

The possibility of using surface modification of cheap metals to make them effective electrode materials has been mentioned (Section 57.3.2.3(1)). A further example employs cyanoferrates and cyanoruthenates as the redox centres.76 Complexes such as [M(CN)5L]" (M = Fe, Ru L = CN, H20, NO, L-histidine) may be immobilized on a partially corroded nickel surface. The surfaces have good stability and diffuse reflectance IR spectroscopy shows the presence of bridging cyano groups, implying the presence of a binuclear (Ni, M) species in the surface. A general equation for the redox reaction is ... 

More significantly, when calorimetry is combined with an integral kinetic analysis method, e.g. a spectroscopic technique, we have an expanded and extremely sophisticated method for the characterisation of chemical reactions. And when the calorimetric method is linked to FTIR spectroscopy (in particular, attenuated total reflectance IR spectroscopy, IR-ATR), structural as well as kinetic and thermodynamic information becomes available for the investigation of organic reactions. We devote much of Chapter 8 to this new development, and the discussion will focus on reaction calorimeters of a size able to mimic production-scale reactors of the corresponding industrial processes. 

Because amorphous and crystalline solid-state forms contain nonequivalent spatial relationships at the molecular level, they often display differences in functional group vibrational modes that can be measured by IR spectroscopy. Total attenuated reflectance IR spectroscopy is utilized because it is non-destructive and can be used to directly measure actual tablet and capsule samples. Similarly, solid-state NMR spectroscopy is another non-destructive direct analytical method that can detect and measure differences in nuclear resonance frequencies and relaxations, such as those displayed by amorphous and crystalline material. Cross-polarization... 

A primitive approach to molecular speciation involves identification of the molecular functionalities through the binding energies (BE s) of their constituent elements. This approach has been used to identify electropolymerized poly-pyrrole (9) and N-(0-hydroxybenzyl)anillne/tyrosine (84) films. In the latter case the identification was confirmed with multi-reflection IR spectroscopy. Both examples used either monomers or model compounds as references to generate known comparison spectra. The BE s and peak shapes have also been used to identify the presence of the ferricinium ion on freshly prepared surfaces (85). In this way the identification is similar to fingerprinting. 

ID IQ 2D 2D-NMR 2h2o 2Q 3Q 9BEN A1 ABS AC ACM ACN AFM Al-CSM ALMA-i5 Al-m-EPDM AN AO APT ASTM ATR ATR-IR B/S BABA Two-dimensional Single-quantum One-dimensional Deuteron solid-state NMR Deuterated water Double-quantum Triple-quantum 9 borobicyclo [3, 3, 1] nonane Amide 1 Acrylonitrile-butadiene-styrene terpolymer Accelerator Acrylate rubber Acrylonitrile Atomic Force Microscopy Aluminium salt of chlorosulfonate polyethylene Allyl-rf5 methacrylate Aluminium salt of maleated EPDM Acrylonitrile 1-Allyl oxyoctane Attached Proton Test American Standards for Testing and Materials Attenuated total reflectance spectroscopy Attenuated total reflectance-IR spectroscopy Butadiene/styrene Back-to-back... 

Kustov, L. M., Borovkov, V. Y. and Kazanskii, V. B. Study of ethylene oligomerization on Brpnsted and Lewis acidic sites of zeolites using diffuse reflectance IR spectroscopy. Stud. Surf. Sci. Catal., 1984, 18, 241-247. 

Diffuse reflectance IR spectroscopy has become an attractive alternative to mulls with the introduction of DRIFT cell by Griffiths,29 later modified by Yang.30 Since materials are dispersed in a nonabsorbing medium and not subjected to thermal or mechanical energy during sample preparation, DRIFT spectroscopy is especially suitable for the qualitative/quantitative analysis for polymorphs, which are prone to solid-state transformations. The Kubelka-Munk (K-M) equation,31 which is analogous to Beer s law for transmission measurements, is used to quantitatively describe diffusely-reflected radiation ... 

Diffuse reflection IR spectroscopy was used for determination of grafted amount of polymer. It was evaluated using calibration curves plotted from the absorbency spectra of the samples, made from a mixture of the polymer and particles (50 mg). The characteristic band at 1493 cm-1 was chosen for this estimation. 

Methyl chloride is an important industrial product, having a global annual capacity of ca. 900 000 tons. Its primary use is for the manufacture of more highly chlorinated materials such as dichloromethane and chloroform and for the production of silicone fluids and elastomers. It is usually manufactured by the reaction of methanol with hydrogen chloride with a suitable acid catalyst, such as alumina. To develop a site-specific reaction mechanism and a kinetics model for the overall process, one first needs to identify all the reagents present at the catalyst surface and the nature of their interactions with the surface. The first step in the reaction is dissociative adsorption of methanol to give adsorbed methoxy species. Diffuse reflectance IR spectroscopy (29d) showed the expected methoxy C-H stretch and deformations, but an additional feature, with some substructure, at 2600 cm was... 

The nature of OA interaction with SC lipids in vivo was of significant interest, particularly in light of the IR results above. Reflectance IR spectroscopy in conjunction with the use of a deuterated probe once again proved to be a valuable approach for the noninvasive evaluation of this enhancer in humans [153]. Prior to treatment, test sites on the inner ventral forearm of volunteers were cleansed with water, after which the subject remained at constant temperature and relative humidity, while three pretreatment spectra were collected. The experimental site on one arm was treated with a 5% v/v solution of perdeuterated oleic acid ( H-OA) in ethanol, while the control site, on the contralateral arm, was treated with ethanol alone. Both formulations were applied under occlusion for 16 hours posttreatment, the sites were swabbed clean with ethanol and then air-exposed for 2 hours to allow the occluded skin to dry. An ATR-IR spectmm of the dosed site was then obtained. This site was then tape stripped once and a second spectral examination was made. This sequential tape stripping and spectral acquisition was repeated -20 times in order to obtain an incremental spectral profile as a function of SC depth (defined by the cumulative weight of SC removed with tape stripping). IR spectra thus collected yielded the following information (a) the distribution... 

Fig. 431 Calibration curve for the presence of cefepime dihydrochloride dihydrate in cefepime dihydrochloride monohydrate as determined by diffuse reflectance IR spectroscopy. (From Bugay 1999, with permission.)...

Most of the solvents used in electrochemistry, and particularly water, present strong absorption in the mid-IR range. Therefore the use of external reflection IR spectroscopy for the in-situ observation of electrode processes requires a considerable reduction in the solution thickness in the path of the IR beam. Only a very thin layer of electrolyte between electrode and IR window is allowed in order to have enough energy reaching the electrode surface. Typically, the thickness of the solution layer produced by a well-positioned, flat-polished electrode is of the order of 1 - 5 pm. Within this cavity, which has been described by Yeager et al. as diffusionally decoupled, migration is the predominant form of mass transport [26]. 

For ferromagnetic cobalt particles in zeolite X, spin-echo ferromagnetic resonance has been used to obtain unique structural information (S6). In addition, study of the catalytic signature of metal/zeolite catalysts has been used by the groups of Jacobs (87), Lunsford (88), and Sachtler (47,73,89). Brpnsted acid protons are identified by their O—H vibration (90,91) in FTIR or indirectly, by using guest molecules such as pyridine or trimethylphosphine (92,93). An ingenious method to characterize acid sites in zeolites was introduced by Kazansky et al., who showed by diffuse reflection IR spectroscopy that physisorbed H2 clearly discerns different types of acid sites (94). Also, the weak adsorption of CO on Brpnsted and Lewis acid sites has been used for their identification by FTIR (95). The characterization of the acid sites was achieved also by proton NMR (96). 

Adsorption of albumin, y-globulin, and fibrinogen from single solutions onto several hydrophobic polymers was studied using internal reflection IR spectroscopy. The adsorption isotherms have a Langmuir-type form. The calculated rate and amount of protein adsorbed was dependent on the polymer substrate and the flow rate of the solution. Competitive adsorption experiments were also investigated to determine the specific adsorption of each I-labelled protein from a mixture of proteins. Platelet adhesion to these proteinated surfaces is discussed in relation to a model previously proposed. 

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