Spectroscopy, infrared measurement

Frohlich, H. Using Infrared Spectroscopy Measurements to Study Intermolecular Hydrogen Bonding, /. Chem. Educ. 1993, 70, A3-A6. 

Iwahashi, M. Hayashi, Y. Hachiya, N. Matsuzawa, H. Kobayashi, H., Self-association of octan-l-ol in the pure liquid state and in decane solutions as observed by viscosity, selfdiffusion, nuclear magnetic resonance and near-infrared spectroscopy measurements, J. Chem. Soc. Faraday Trans. 89, 707-712 (1993). 

Summarizing, infrared spectroscopy measures, in principle, force constants of chemical bonds. It is a powerful tool in the identification of adsorbed species and their bonding mode. Infrared spectroscopy is an in situ technique, which is applicable in transmission or diffuse reflection mode on real catalysts, and in reflection-absorption mode on single crystal surfaces. Sum frequency generation is a speciality... 

Infrared spectroscopy measures the frequency or wavelength of light absorbed by the molecules caused by transitions in vibrational energy levels (Vollhardt and Schore... 

FTIR Spectroscopy and Mechanisms on Electrode. The basis of Fourier transform infrared spectroscopy was described in Section 6.2.6. One of the more difficult aspects of detecting the mechanism of electrode reactions is that of knowing the nature of the intermediate radicals on the electrode surface. Infrared spectroscopy measures chemical bonds, so it is an ideal method for detecting which bonds are present and hence which intermediate radicals are taking part in a surface reaction at a given potential, etc. 

Infrared spectroscopy measurements on YB66 reveal a strong absorption band around 130 cm-1 which is though to be due to the local vibration of yttrium atoms (Werheit et al., 1991). 

Thus, the SIMS intensity ratios sensitively reflect the transition from zirconium ethoxide to zirconium oxide, and indicate that this reaction takes place at temperatures between 300 and 400 °C. Infrared spectroscopy measured in transmission confirms the disappearance of ethoxide groups at the same temperatures at which the SIMS ZrO+/Zr+ and ZrC>2+/Zr+ intensity ratios change to those characteristic of Zr02. Whilst the infrared spectra might also be due to free ethoxide ligands on the support, the inherent advantage of SIMS is that it confirms -albeit indirectly - that the ethoxide ligands are connected to zirconium [17]. 

However, due to a different experimental setup, the assignation of these species could not be confirmed from the infrared spectroscopy measurements carried out on a gold catalyst in alkaline medium, " which was found to present an exclusive series of oxygen reduction pathway. " The presence of these species as intermediates in the ORR mechanism was observed by Raman spectroscopy coupled with electrochemistiy in acidic medium on a gold electrode with bismuth adatoms. " Later, this mechanistic study of ORR by Raman spectroscopy was extended to a gold electrode in alkaline medium "" with an evidence for O2 formation as a reaction intermediate. H02 was also identified, but as a product of the ORR in alkaline medium. 

In the case of iron phthalocyanine catalyst dispersed on carbon, infrared spectroscopy measurements enabled to confirm the series mechanistic pathway for the ORR in the high overpotential domain (below 0.7 V vs RHE). Two intermediates species, 02 and H02 and two products, water (majority product) and hydrogen peroxide could be identified. However, since only few studies are led on the oxygen reduction reaction by infrared spectroscopy, a confident attribntion of the different vibrational transitions observed to a particnlar intermediate remains difficult. 

Fig. 2. A schematic illustration of the difference of scattering intensities between the IR/Raman and neutron scattering techniques to the relationship of dispersion curves. For instance. Infrared spectroscopy measures frequencies at the BZ centre, q = 0, the peaks shown are relatively sharp, the width of the peaks is determined by the resolution of the instrument used. In an INS experiment, a broadened spectrum for each dispersion curve was observed the spectrum has higher intensity at the flat part ojf the dispersion curve at the BZ boundary. Hence the mode assignment is not appropriate for the INS spectrum.

Infrared spectroscopy measurements were performed using a Perkin Elmer 580 apparatus. The acid strength distribution of the samples was measured using both calorimetric and volumetric gas-solid titration. Ammonia, pyridine, and branched pyridines (2,6-lutidine and 3,5-lutidine) were the selected probes. They were further dried over activated 3A molecular sieve extrudates and were purified by freeze-thaw techniques. 

Coll-Martinez, M. K. Morgan, P. G. Cooper, and S. N. Hunyor, Cerebral Tissue Oxygen Saturation (Sr02) from Near-Infrared Spectroscopy Measurements Following 90 Degrees-Head-Up Tilt, Adv. Exp. Med. Biol., 471, 125-131 (1999). 

An alternative model can be proposed for describing the CO oxidation by NO which assiunes a preferential adsorption of NO on Rh and of CO on Pt as mentioned by Van Slooten and Nieuwenhuys [11] who investigated this reaction on a Pt-Rh/SiOj catalyst by means of infrared spectroscopy measurements. However this situation leads to a more complex description of the rate limiting step (3) as far as the nature of the vacant nearest neighbour adsorption site to dissociate NO is concerned. This one can be Pt alone, Rh alone or either Pt or Rh. According to these different assumptions the following reactions steps for tlie dissociation of NO can be considered. 

The nature of the superficial copper species accessible to CO and NO was deduced fiom infrared spectroscopy measurements. 

Infrared spectroscopy measures the absorption of light by molecules in the infrared region of the spectrum, which provides information on the types of functional groups present in a molecule. For example, looking at the infrared spectrum can provide evidence as to whether certain pairs of atoms are bonded by one, two, or three pairs of electrons. The shapes of the peaks in an infrared spectrum can also be used to gain information about intermolecular interactions between the species we are looking at and the surrounding medium. 

C. Pennekamp, M. Bots, L. Kappelle, et al.. The Value of Near-Infrared Spectroscopy Measured Cerebral Oximetry during Carotid Endarterectomy in Perioperative Stroke Prevention A Review, Eur.. Vase. Endovasc. Surg., 38, 539 (2009). 

Routine infrared spectroscopy measures the absorption of an incident radiation as a function of the frequency or, equivalently, of the energy transferred... 

As it was shown by SNIFTIRS measurements (subtractively normalized interfacial Fourier transform infrared spectroscopy measurements) that adsorbed CO species exist from 0.3 V vs RHE on a Pt surface ... 

Raman spectroscopy uses an incident laser beam that is focused on the sample. The intensity of the scattered light is measured as a function of its frequency. Bands appear in the spectrum that are shifted in frequency from the frequency of the incident light. Each shift in frequency corresponds to one of the vibrational frequencies of the molecule. Infrared spectroscopy measures the absorption of infrared light as a function of its frequency. Absorption bands appear in the spectrum that correspond to vibrational frequencies in the DNA. Infrared spectroscopy is hindered by the strong almost continuous absorption band of water while Raman spectroscopy benefits from the fact that water is a weak Raman scatterer. Infrared spectroscopy is of greater usefulness in the studies of films and fibers while Raman is of use in obtaining the vibrational frequencies of DNA in crystals, films, fibers, and aqueous solutions. A large amount of evidence, both theoretical and experimental, now exists which shows that there is a close relation between the conformation of a DNA and the frequencies and the intensities of certain bands in the Raman spectra. The theory for the relation between the frequencies and intensities and the DNA conformation is outlined in the next two sections. 

For small prisms, [/i = 10 nm) the absorption and scattering spectra present only two peaks these features could be attributed to the in-plane dipole resonance (longer wavelengths) and to the inplane quadrupole resonance [44]. By increasing the side of the triangle, a clear red-shift of these two peaks appears (see Fig. 3.8) and this is also confirmed experimentally by ultraviolet-visible-near-infrared spectroscopy measurements [44]. This effect can be understood by considering the fact that by enlarging the area of... 

Infrared spectroscopy measures vibrational excitation. The energy of the incident radiation ranges from about 1 to 10 kcal mol (A 2.5 — 16.7 /xm v 600 000 cm ). Characteristic peaks are observed for certain functional groups, a consequence of stretching, bending, and other modes of vibration, and their combination. Moreover, each molecule exhibits a characteristic infrared spectral pattern in the fingerprint region below 1500 cm. ... 

Table 3 Values of induction time from infrared spectroscopy measurements for evolution of carbonyl absorption [78]...

Infrared spectroscopy measures the light absorbed by different types of vibrations in molecules. 

The most reliable (time-consuming and costly) identification method is to use infrared spectroscopy measurements to determine the material. The Rapra Collection of Infrared Spectra of Rubbers, Plastics, and Thermoplastic Elastomers can be used to compare the spectrum of a test material to reference spectra. The transmission spectra in this reference are obtained either from cast or molded thin film or in the case of cross-linked materials by pyrolysis of the material in a Pyrex tube. 

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