FT-infrared

Fig. 3 Fourier transform (FT) infrared (upper) and FT-Raman (lower) spectra of aspirin. The left ordinate scale is representative of the Raman intensity, whereas the right ordinate scale represents IR transmission units. 

Effluent gas emerging from a gas chromatograph at atmospheric pressure can be led directly into a heated infrared gas cell via a heated transfer line. Vapour-phase infrared spectra of eluting components can be recorded as they pass through a cell by a Fourier transform (FT) infrared spectrometer enabling a full-range spectrum to be collected and stored in a second or less. 

Yasenkov, S. and Frei, H. (1998). Time-resolved FT-infrared spectroscopy of visible light-induced alkene oxidation by 02 in a zeolite. J. Phys. Chem. B 102, 8177-8182... 

Fourier spectroscopy, 23 137 Fourier transformation, essential equations for, 14 226-227 Fourier transform (FT) infrared (ftir) analysis, 19 563-564, 813. See also Microscopy-ftir technique dichroism, in silicone network characterization, 22 569 instruments, 23 138 advantages of, 14 228 resolution for, 14 227 microscopy, 14 232... 

Infrared spectra. An FT infrared spectrum of HTE liquid polymer (fan -500) is shown in Figure 2. All spectra of HTE polymers show characteristic absorptions a broad band at 3530 cm-1- for the hydroxyl stretching, three bands at 2958, 2913, and 2875 cm-1 assigned to the carbon-hydrogen stretching, an extremely strong... 

In the absence of suitable crystals for an X-ray structural study, combinations of FTIR, RR, XAS, EPR, ENDOR, XANES, and ESEEM spectroscopies were used to characterize the manganese site in the OEC. Vibrational spectroscopy, particularly low-frequency FT infrared and... 

Selected entries from Methods in Enzymology [vol, page(s)] Application in fluorescence, 240, 734, 736, 757 convolution, 240, 490-491 in NMR [discrete transform, 239, 319-322 inverse transform, 239, 208, 259 multinuclear multidimensional NMR, 239, 71-73 shift theorem, 239, 210 time-domain shape functions, 239, 208-209] FT infrared spectroscopy [iron-coordinated CO, in difference spectrum of photolyzed carbonmonoxymyo-globin, 232, 186-187 for fatty acyl ester determination in small cell samples, 233, 311-313 myoglobin conformational substrates, 232, 186-187]. 

The nature of the titanium-containing active site has been investigated with different techniques, including theoretical calculations. The formation of a hydroperoxidic species or of a bidentate side-on titanium peroxo structure was suggested by many authors . Alternatively, some DFT calculations indicated an undissociated molecule of H2O2 weakly interacting with Ti centers or an active Ti-O-O-Si peroxo moiety as a reactive site . Recently, Lin and Frei reported the first direct detection, obtained using in situ FT-infrared spectroscopy, of a Ti-OOH moiety as active species in the oxidation of small olefins like ethylene or propylene . 

FT-Infrared spectroscopy was accomplished employing KBr pellets, using a Galaxy Series FT-IR 4020, Mattson Inst., Madison, WI. Thermal analysis was done employing a Dupont Thermal Instrument Model 990 employing a heating rate of 20 °C/min and a gas flow rate of 0.1 1/min. 

ATR spectroscopy in the infrared has been used extensively in protein adsorption studies. Transmission IR spectra of a protein contain a wealth of conformational information. ATR-IR spectroscopy has been used to study protein adsorption from whole, flowing blood ex vivo 164). Fourier transform (FT) infrared spectra (ATR-FTIR) can be collected each 5-10 seconds165), thus making kinetic study of protein adsorption by IR possible 166). Interaction of protein with soft contact lens materials has been studied by ATR-FTIR 167). The ATR-IR method suffers from problems similar to TIRF there is no direct quantitation of the amount of protein adsorbed, although a scheme similar to the one used for intrinsic TIRF has been proposed 168) the depth of penetration is usually much larger than in any other evanescent method, i.e. up to 1000 nm water absorbs strongly in the infrared and can overwhelm the protein signal, even with spectral subtraction applied. 

The use of phosphorus-based flame retardants in combination with other, better established, flame retardants is most effective in situations in which the combination proves synergistic. However, as yet our understanding of such synergistic effects is far from complete and more fundamental work is required in this area Work in which the gaseous and solid products of combustion, with and without the presence of flame retardants, are carefully analyzed. Such analyses can now be undertaken more readily than in the past, owing to the relatively recent development of techniques such as gas-phase FT-infrared spectroscopy and laser-pyrolysis time-of-flight mass spectrometry for the identification of volatiles, and solid-state NMR spectroscopy and x-ray photoelectron spectroscopy for the analysis of chars. 

A major reason why XAFS spectroscopy has become a critically useful probe of catalyst structure is the fact that it is easily adapted to characterization of samples in reactive atmospheres. The X-ray photons are sufficiently penetrating that absorption by the reaction medium is minimal. Moreover, the use of X-ray- transparent windows on the catalytic reaction cell allows the structure of the catalyst to be probed at reaction temperature and pressure. For example, the catalyst may be in a reaction cell, with feed flowing over it, and normal online analytical tools (gas chromatography, residual gas analysis, Fourier transform (FT) infrared spectroscopy, or others) can be used to monitor the products while at the same time the interaction of the X-rays with the catalyst can be used to determine critical information about the electronic and geometric structure of the catalyst. 

Spectroscopic methods, such as FT-infrared (FTIR) and Raman spectroscopy detect changes in molecular vibrational characteristics in noncrystalline solid and supercooled liquid states. Various nuclear magnetic resonance (NMR) techniques and electron spin resonance (ESR) spectroscopy, however, are more commonly used, detecting transition-related changes in molecular rotation and diffusion (Champion et al. 2000). These methods have been used for studies of the amorphous state of a number of sugars in dehydrated and freeze-concentrated systems (Roudaut et al. 2004). 

Various compounds Ecdysteroids Lychnis flos-coculi RPC DAD UV, FT-infrared and 179... 

Nowadays, most instruments use a FT-infrared (FT-IR) system, a mathematical operation used to translate a complex curve into its component curves. In an FT-IR instrument, the complex curve is an interferogram, or the sum of the constructive and destructive interferences generated by overlapping light waves, and the component curves are the IR spectrum. The standard IR spectrum is calculated from the Fourier-transformed interferogram, giving a spectrum in percent transmittance (%T) versus light frequency (cm ). 

Another problem when embarking on synthesis on sohd supports is the difficulty in analyzing compounds attached to the at support Methods arex available for analyzing compounds on individual beads, such as magic-angle spiiming NMR or FT-infrared spectroscopy, but these are too demanding to be carried out on a routine basis on a multitude of beads. 

Figure 7.13. Exchange at room temperature on Ceo.esZrosrOi, followed by FT-infrared, between O2 surface species (formed upon oxygen adsorption) and 02 from the gas phase.

FT-Infrared Spectroscopy and IR-Microscopy On-Bead Analysis of Solid-Phase Synthesis... 

The instrument that determines the absorption spectrum for a compound is called an infrared spectrometer or, more precisely, a spectrophotometer. Two types of infrared spectrometers are in common use in the organic laboratory dispersive and Fourier transform (FT) instruments. Both of these types of instruments provide spectra of compounds in the common range of 4000 to 400 cm" Although the two provide nearly identical spectra for a given compound, FT infrared spectrometers provide the infrared spectrum much more rapidly than the dispersive instruments. 

D. Naumann, Chapter 9, FT-Infrared and FT-Raman spectroscopy in biomedical research in Infrared and Raman Spectroscopy of Biological Materials ed. H. Ulrich and G.B. Yan, Practical Spectroscopy Series, Vol. 24, Taylor Francis Group, London, 337-350, 2000. 

---