Fourier transform infrared absorption spectroscopy

Fourier-transform infrared absorption spectroscopy was performed on Mg-doped GaN grown by MOCVD [9], The as-grown sample was semi-insulating and displayed an LVM at 3125 cm 1. After... 

Also, Fourier transform infrared absorption spectroscopy provides relevant information regarding the specific interactions of different probes within substrates [17], especially in the diffuse-reflectance mode when applied to the study of powdered opaque surfaces that disperse the incident radiation. The extension of this technique to obtain time resolved transient absorption spectra in the IR wavelength range (laser flash-photolysis with IR detection) will certainly play in the near future an important role in terms of clarifying different reaction mechanisms in the surface photochemistry field [17c, 18]. 

Fourier transform infrared absorption spectroscopy (FTIR)... 

J. Shirahata, T. Ohori, H. Asami, T. Suzuki, T. Nakayama, H. Suematsu and K. Niihara Fourier-Transform Infrared Absorption Spectroscopy of Chromium Nitride Thin Film , Jpn. J. Appl. Phys., 50, 01BE03 (2011)... 

Tsugane et al. used Fourier transform infrared absorption spectroscopy to investigate the dimerization reaction of benzoic acid in saturated supercritical... 

Infrared spectroelectrochemical methods, particularly those based on Fourier transform infrared (FTIR) spectroscopy can provide structural information that UV-visible absorbance techniques do not. FTIR spectroelectrochemistry has thus been fruitful in the characterization of reactions occurring on electrode surfaces. The technique requires very thin cells to overcome solvent absorption problems. 

Reaction products can also be identified by in situ infrared reflectance spectroscopy (Fourier transform infrared reflectance spectroscopy, FTIRS) used as single potential alteration infrared reflectance spectroscopy (SPAIRS). This method is suitable not only for obtaining information on adsorbed products (see below), but also for observing infrared (IR) absorption bands due to the products immediately after their formation in the vicinity of the electrode surface. It is thus easy to follow the production of CO2 versus the oxidation potential and to compare the behavior of different electrocatalysts. 

Fourier-transform infrared (FTIR) spectroscopy Spectroscopy based on excitation of vibrational modes of chemical bonds in a molecule. The energy of the infrared radiation absorbed is expressed in inverse centimeters (cm ), which represents a frequency unit. For transition-metal complexes, the ligands -C N and -C=0 have characteristic absorption bands at unusually high frequencies, so that they are easily distinguished from other bonds. The position of these bonds depends on the distribution of electron density between the metal and the ligand an increase of charge density at the metal results in a shift of the bands to lower frequencies. 

In 1993, Blatter and Frei [34] extended the Aronovitch and Mazur [28] photo-oxidation into zeolitic media, which resulted in several distinctive advantages as described below. Irradiation in the visible region (633 nm) of zeolite NaY loaded with 2,3-dimethyl-2-butene, 16, and oxygen resulted in formation of allylic hydroperoxide, 17, and a small amount of acetone. The reaction was followed by in situ Fourier-transform infrared (FTlR) spectroscopy and the products were identified by comparison to authentic samples. The allylic hydroperoxide was stable at - 50°C but decomposed when the zeolite sample was warmed to 20°C [35]. In order to rationalize these observations, it was suggested that absorption of light by an alkene/Oi charge-transfer complex resulted in electron transfer to give an alkene radical cation-superoxide ion pair which collapses... 

PAS spectra are similar to those obtained using ordinary Fourier transform infrared (FTIR) spectroscopy except truncation of strong absorption bands which occurs due to photoacoustic signal saturation. PAS allows the structure to be studied at different thicknesses because the slower the frequency of modulation, the deeper the penetration of IR radiation. 

One other in situ technique can be used to determine fractional acidity in atmospheric aerosols by means of Fourier transform infrared (FTIR) spectroscopy (46). Originally, impactor samples were collected and were pressed into a KBr matrix, and then the IR spectrum was taken by attenuated total reflectance (ATR) FTIR spectroscopy to determine relative acidity, based on differences in absorption bands for sulfate and bisulfate species. Aerosols with [H+]/[S042 ] ratios greater than 1 could also be qualitatively identified. More recent innovations in the FTIR technique (47, 48) have made possible... 

Fig. 1. (a) THz absorption spectra from Kemp et al. [38]. (b) Comparison study of transmission spectra of RDX using THz-TDS and Fourier Transform Infrared (FTIR) spectroscopy with data from Kemp et al. and Huang et al [39]. The dashed line is RDX from Kemp et al. The other curves are from Huang et al., where the bottom curve is RDX measured by THz-TDS, the solid curve is RDX measured by FTIR, and the top curve... 

Shanmugam G, Polavarapu PL, Gopinath D, Jayakumar R (2005) The structure of antimicrobial pexiganan peptide in solution probed by Fourier transform infrared absorption, vibrational circular dichroism, and electronic circular dichroism spectroscopy. Biopolymers 80 636-642... 

For the assay of enzymes with products and reagents that have no absorption, fluorescence or luminescence in the ultraviolet or visible region, developments in analytical infrared spectroscopy can be used. In particular, mid-Fourier transform infrared (mFTIR) spectroscopy has been successfully applied to the determination of enzyme activities and kinetics, e.g. of /i-fructosidasc, phosphoglucose isomerase and polyphenol oxidase [90]. The method could very well be a tool that may also be applied to a variety of other enzyme classes. The potential of high-throughput applications, however, has yet to be demonstrated. 

Characterize new electrocatalysts by high-resolution transmission electron microscopy (HRTEM), in-situ fourier transform infrared (FTIR) spectroscopy and extended x-ray absorption fine structure (EXAFS) techniques. 

These polyurethanes (and their precursors or analogues) were cast from an appropriate solvent, usually DMF, onto the glass bead surfaces used in the in vitro test for platelet retention (4), or for the thrombin absorption test used previously (2). Crystals of KBr for Fourier transform infrared (FTIR) spectroscopy and glass microscopic slides for examination by XPS (ESCA) served as supports for polymers cast from the same solvents. Concentration of polymer (5 wt %), temperature of casting... 

The first efforts towards real-time and in-line monitoring of CO2 absorption processes focused on the use of Fourier transform infrared (FTIR) spectroscopy in combination with a multivariate model. Geers et al. (3) successfully applied this methodology to a solvent consisting of an equimolar solution of p-alanine and potassium hydroxide. They predicted the concentrations of the amine, of absorbed CO2 and SO2, and also included the effect of NO2 in their analysis. 

Fourier transform infrared (FTIR) spectroscopy can be used as a tool to study the ciystalline and amorphous fractions (Chuah, 2001 Ouchi et al., 1977 Bulkin et al., 1987 Ward and Wilding, 1977 Yamen et al., 2008) of PTT. The absorption bands of IR between 1750-800 cm are helpful to estimate the fraction of the ciystalhne phase of PTT samples. The assignment of the absorption bands in this region for PTT was proposed by Yamen et al. (2008) (Table 7). 

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