FTIR spectroscopic measurements

Junkermann, W., and T. Ibusuki, FTIR Spectroscopic Measurements of Surface Bound Products of Nitrogen Oxides on Aerosol Surfaces—Implications for Heterogeneous HN02 Production, Atmos. Enriron., 26A, 3099-3103 (1992). 

Fluorinated chromia used to catalyze the isomerization reaction of CHF2CHF2 to CF3CH2F, also exhibited evidence for the importance of chromium in higher oxidation states. FTIR spectroscopic measurements of CO adsorption confirmed the occurrence of Cr4+ and Cr5+ on the surface of chromia catalysts before being used [52]. During the activation, Cr4+ and Cr5+ sites were reduced and enhanced activity of the catalyst was observed. The reaction pathway proposed for isomerization involves the formation of hydrogen fluoride due to the degradation reaction of the fluoroalkane. 

Detroit, Mi., 3rd-7th May 1992, p.211-4. 012 ON-LINE FTIR SPECTROSCOPIC MEASUREMENT OF ERUCAMIDE AND SILICA IN MOLTEN LDPE Fidler R A... 

Miniaturized chemical analysis systems have been developed for most macroscopic counterparts (Dittrich et al. 2006). The availability of optical fibers, light sources, and detectors in the visible UV and near-infrared (NIR) wavelengths makes it possible to integrate spectroscopic measurements in microreactors (Lobbecke et al. 2005). Fourier transform infrared spectroscopy (FTIR) is an efficient, broadly applicable... 

Instrumentation characterization of PIDAA derivatives was by NMR and FTIR spectroscop. All NMR spectra were measured on a JEOL GSX-270 instrument using DMSO-J(5 as the solvent and tetramethylsilane (TMS) as a reference at 0.00 ppm. The standard uncertainties are 0.02 ppm for H-NMR and 0.05 ppm for C-NMR, respectively. FTIR spectra of solids were recorded in KBr pellets on a Nicolet Magna 550 FTIR. 

In situ spectroscopic measurements of a catalytic system provide a considerable opportunity to determine the chemical species present under reactive conditions. FTIR and NMR have been the two most frequently used in situ spectroscopic methods (see Chapters 2 and 3). They have been successfully used to identify labile, non-isolatable transient species believed to be involved in the catalytic product formation. Furthermore, efforts have been made to use this information in order to obtain more detailed kinetics, by decoupling induction, product formation, and deactivation. Thus, in situ spectroscopic techniques have the potential for considerably advancing mechanistic studies in homogeneous catalysis. 

The quality of the system identification results is strongly dependent on the manner in which the spectroscopic measurements are made. In this regard, the time-scale of the individual spectral measurements Tgpect is crucial. Many good resolution FTIR, Raman, UV-VIS, fluorescence and H, F,"P NMR spectra can be obtained in 100 s or less. Also, many VCD, ECD, and 2D NMR spectra can be obtained in 1000 s or less. 

N, adsorption for determination of pore size distribution(BJH method) using a Micrometries ASAP 2000 automatic analyzer. FTIR spectra were recorded on a PerkinElmer 221 spectrometer and UV-vis spectroscopic measurments were carried out using Varian CARY 3E double beam spectrometer in the range of 190 - 820 nm. 

With the FTIR spectroscopic method, these free radical reactions cannot be studied individually under completely isolated conditions since competing side reactions and also secondary reactions involving the molecular products must be taken into account. These mechanistic complications can be greatly reduced by appropriate selection of the method of free radical generation, as described in Section II.B. In general, to minimize the occurrence of secondary reactions, the conversion of the molecular reactants, and consequently the product yields, have to be kept as small as is permissible in order to obtain accurate concentration measurements. Also, the reaction time required for such chemical analysis must be kept as short as possible to minimize photochemical and heterogeneous losses of labile products. 

This unit describes the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic method (AOCS, 1999a AOAC International, 2000), a novel method for measuring the total amount of fat with isolated trans double bonds. It is applicable to natural fats (ruminant fats) and processed fats and oils (partially hydrogenated fats and oils or refined vegetable oils) consisting of long-chain fatty acid methyl esters or triacylglycerols with trans levels >5%, as percent of total fat (AOAC International, 2000). 

IR spectroscopy is one of the oldest spectroscopic measurements used to identify and quantify materials in on-line or near-line industrial and environmental applications. Traditionally, for analyses in the mid-IR, the technologies used for the measurement have been limited to fixed wavelength NDIR filter-based methods and scanning methods based on either grating or dispersive spectrophotometers or interferometer-based FTIR instruments. The last two methods have tended to be used more for instruments that are resident in the laboratory, whereas filter instruments have been used mainly for process, field-based and specialist applications, such as combustion gas monitoring. 

The surface-modified PE films were characterised using XPS and ATR-FTIR spectroscopic techniques. The hydrophilicity of the modified surfaces was determined by measuring their contact angle with water. 

IR spectroscopic imaging offers the advantage of fast measurements with lateral resolution of a few micrometers. Due to the high acquisition rate of spectral data even dynamic systems can be studied at a time resolution of seconds. This report will demonstrate the unique opportunities by FTIR spectroscopic imaging to investigate material characterized by small thickness of the sample layer and non-crystalline state. SPR imaging is a new technique based on the classical SPR that combines high sensitivity with excellent lateral reso-... 

FTIR spectroscopic imaging provides new opportunities for the investigation of material having small layer thickness, non-crystalline state and domain size of few micrometers. Samples may even exhibit all three properties at once, as it is the case for microstructured polymer membranes. This is a particular advantage of the new measuring approach. Domain sizes may even be reduced to the upper nanometer range if Raman spectroscopic mapping is employed [20],... 

Figure 13 Typical FTIR spectra obtained from nickel electrodes polarized to 0.2 V (Li/Li+) in LiBF4 1 M solution and measured ex situ, external reflectance mode (after being washed and dried), (a) The electrode was taken out of solutions soon after the surface films were formed, (b) The spectrum was measured after the electrode was stored for 1.5 h at open circuit for 1.5 h. (c) Same as (b), storage for 3.5 h at OCV before the spectroscopic measurement [34]. (With copyright from The Electrochemical Society Inc.)...

We examined the representative esters, y-butyrolactone (BL), methyl formate (MF), and methyl acetate (MA). Figures 16 and 17 show FTIR spectra measured (ex situ) from noble metal electrodes polarized to low potentials in LiC104 solutions of BL and MF, respectively [30,39], As shown in these figures, at the onset reduction potential of around 1.3-1.2 V (Li/Li+), stable surface films precipitate on the electrode surfaces. Table 1 shows the spectral analysis for the surface films formed on noble metals at low potentials in BL. The conclusion drawn from the spectroscopic study is that the major surface compound formed is the dilithiated cyclic P-keto ester, which is similar to the electrolysis product of BL in TAA salt solutions (Scheme 2). 

In the case of LiC104, there is some spectroscopic evidence of anion reduction below 1.5 V [39], The stable surface species which may precipitate due to the Cl()4 reduction is, among others, Li20. We have no spectroscopic evidence for precipitation of stable LiC10x (x = 1-3) or for LiCl onto noble metals at potentials above those of Li bulk deposition. In any event, the above salt anion reduction processes do not dominate the overall surface film formation on nonactive electrodes at low potentials in most aprotic solvents. Thus, both anions can be considered as only moderately reactive. The onset potential for the reduction of the anions from the third group is about 2 V (Li/Li+). This is clearly demonstrated in Figures 18 and 19, which show FTIR spectra measured in situ from... 

The experimental consideration for the performance of ex situ and in situ FTIR spectroscopic studies of Li electrodes was reported in detail in Refs. 48, 85, 108, 131, 157, 175 and 176. A schematic description of the FTIR measurement modes is shown in Figure 9. Surface Raman could also be considered as a promising technique for the analysis of the surface layers in lithium electrodes (and can be applied in situ). It also provides information on the vibrational states of materials and, thus, the identity of functional groups. However, we found that this technique is destructive for Li surfaces since the laser beam causes visible decoloration of Li surfaces during Raman measurements [187],... 

In spite of the experimental difficulty of using infrared spectroscopy to study the surface structure of carbon, IR spectroscopic measurements (especially in the form of Fourier transform IR, FTIR) have brought to light important information on the changes in surface chemistry produced by oxidation and substitution reactions. As a result of the systematic FTIR studies of Starsinic et al. (1983), van Driel (1983) and others (see Zawadzky, 1989 Boehm, 1994), considerable progress has been made in the assignment of IR bands. 

For the IR (Perkin-Elmer 1730 FTIR) spectroscopic studies self-supported wafers were pressed from the zeolite powder with a thickness of 15 mg/cm . The wafers were placed into a sample holder inside a pyrex glass cell with KBr windows, which allowed pretreatment (773 K, 1 hr, vacuum <10 Torr), introduction of probes, after cooling to the desired temperature, and registration of the spectra at 295 K. Three types of IR experiments were run (i) stepwise loading (0.1-6 Torr) the wafers with adsorbates at 295 K, (ii) generation of surface species with increasing temperature in the presence of adsorbate (closed cell), and (iii) loading adsorbate at 453 K followed by detection of surface species formed with time (1-240 min) at the same temperature. After each set of IR measurement the same sample was analyzed by UV-VIS spectroscopy. 

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