Showing papers on "Infrared spectroscopy published in 1978"

Infrared and Raman Spectra of Inorganic and Coordination Compounds

Abstract: Inorganic molecules (ions) and ligands are classified into diatomic, triatomic, four-atomic, five-atomic, six-atomic, and seven-atomic types, and their normal modes of vibration are illustrated and the corresponding vibrational frequencies are listed for each type. Molecules of other types are grouped into compounds of boron, carbon, silicon, nitrogen, phosphorus, and sulfur, and the structures and infrared (IR)/Raman spectra of select examples are shown for each group. Group frequency charts including band assignments are shown for phosphorus and sulfur compounds. Other group frequency charts include hydrogen stretching frequencies, halogen stretching frequencies, oxygen stretching and bending frequencies, inorganic ions, and metal complexes containing simple coordinating ligands. Keywords: inorganic compounds; coordination compounds; diatomic molecules (ligands); triatomic molecules (ligands); four-atomic molecules (ligands); five-atomic molecules (ligands); six-atomic molecules (ligands); seven-atomic molecules (ligands); boron compounds; carbon compounds; silicon compounds; nitrogen compounds; phosphorus compounds; sulfur compounds; group frequency charts

Fourier Transform Infrared Spectroscopy: Applications to Chemical Systems

Abstract: P.C. Gillette, J.B. Lando, and J.L. Koenig, A Survey of Infrared Spectral Data Processing Techniques. P.L. Polavarapu, Fourier Transform Infrared Vibrational Circular Dichroism. K. Krishnan, Advances in Capillary Gas Chromatography*b1Fourier Transform Interferometry. A.G. Nerheim, Applications of Spectral Techniques to Thermal Analysis. P. Painter, M. Starsinic, and M. Coleman, Determination of Functional Groups in Coal by Fourier Transform Interferometry. J.R. Ferraro and A.J. Rein, Applications of Diffuse Reflectance Spectroscopy in the Far-Infrared Region. J.D. Swalen and J.F. Rabolt, Characterization of Orientation and Lateral Order in Thin Films by Fourier Transform Infrared Spectroscopy. W.G. Golden, Fourier Transform Infrared Reflection*b1Absorption Spectroscopy. J.A. Graham, W.M. Grim III, and W.G. Fateley, Fourier Transform Infrared Photoacoustic Spectroscopy of Condensed-Phase Samples. Each chapter includes references. Index.

The OH stretching region infrared spectra of low density amorphous solid water and polycrystalline ice Ih

Abstract: The transmission spectra in the intramolecular stretching region have been measured for thin films of H2O and D2O polycrystalline ice Ih and amorphous solid water. The data have been reduced to obtain the complex refractive index in this region via an iterative procedure designed to account for reflection and interference losses. Details of this procedure are described. The values which result from this analysis are converted to give the imaginary part of the dielectric permittivity as a function of wavelength for each sample. In this form the spectra are examined and compared to one another, with regard to recent experimental and theoretical studies. We conclude that it is difficult to obtain detailed structural information for the amorphous solid from an analysis of the OH (OD) stretching vibrational spectrum alone.

Fourier transform infrared spectroscopic study of the structure of silane coupling agent on E-glass fiber

Abstract: Infrared spectra of silane coupling agents deposited on E-glass fiber were obtained by Fourier transform infrared spectroscopy (FT-IR). A spectral subtraction technique resolved all vibrational modes of the coupling agent deposited from various concentrations of treating solutions. The amount of vinyl functional coupling agent was determined by measuring the integrated peak intensities of the organic functional group. It revealed that the thickness of the coupling agent layer on the glass fiber depended on the concentrations of the treating solution. The rates of condensation reaction of polysiloxanol with and without glass fiber were followed. The coupling agent on the glass fiber reacted much faster than without glass at room temperature. It was concluded that the coupling agent molecules near the glass fiber surface have some order and can easily participate in the condensation reaction. The carbonyl group of a methacryl functional silane hydrogen bonds with hydroxyl groups. The methacryl functional silane on the glass fiber showed less hydrogen bonded groups than the precipitated polysiloxanol suggesting a mechanism of predominant head-to-head adsorption.

Influence of the intermolecular charge transfer interaction on the solution and solid state infrared spectra of 7,7,8,8-tetracyanoquinodimethane (TCNQ) alkaline salts

Abstract: The results of a study of the effect of concentration on the electronic and infrared absorption spectra of LiTCNQ and Li[2H4]TCNQ in dimethylsulphoxide, as well as the Raman and infrared spectra of aqueous solutions of the same salts, are reported. The formation of the self-dimer of the TCNQ radical anion is accompanied by the appearance of some peculiar absorptions in the infrared. They are attributed to a vibronic intensity enhancement of some vibrational modes of the dimer, corresponding to the out-of-phase coupling of totally symmetric modes of the isolated radicals. The phenomenon is interpreted in terms of the Ferguson–Person vibronic model, which embodies the basic concepts of the charge transfer (CT) interaction.The comparison of the vibronic effects discovered for the TCNQ radical dimer in solution with those reported in the literature for the infrared spectrum of crystalline KTCNQ shows that the dimeric unit essentially contains the same vibronic features induced by the CT interaction in the solid state. The infrared spectra of the two polymorphic forms RbTCNQ(I) and RbTCNQ(II) are also reported. Their comparison shows that the intensity of the vibronic features is sensitive to different types of anion stacking in the two structures.An overall analysis of the reported data allows us to give the complete list of the infrared absorptions of vibronic origin and to reassign some infrared active fundamentals of the monomeric TCNQ radical anion.

The structure of lead silicate glasses determined by vibrational spectroscopy

Abstract: The polarized Raman spectra and infrared powder absorption spectra for PbO ·xSiO2 glasses, with 0.5⩽x⩽2, were measured and interpreted in terms of the structure of the glasses. Comparison of the spectra of the glasses with the spectra of numerous stable and metastable crystalline phases was also made. It was found that the glasses are composed of a number of silicate species. In glasses for whichx is less than 1, the presence of ionic oxygen (oxygen not bonded to silicon) is confidently inferred from the spectra. A new way of deconvoluting the spectra is also reported.

Studies of chlorophyll‐chlorophyll and chlorophyll‐ligand interactions by visible absorption and infrared spectroscopy at low temperatures

Abstract: — A comparison of the visible absorption and infrared spectra of various chlorophyll-chlorophyll (Chl) and Chi-nucleophile aggregates at room temperature and at low temperatures has been made The IR data provide structural information indispensable for the interpretation of the visible spectra As a necessary preliminary, it is shown that Chl a solutions in nonpolar solvents can be prepared by appropriate drying techniques that contain at a conservative estimate ≤ 3 mol % of water (ie Chl a/H2O > 30:1) Very dry solutions of Chl a or Pyrochl a(≥ 10 mM) in toluene or methylcyclohexane-isopentane solution show only slight changes in visible spectra on cooling to 77 K From IR, additional Chl-Chl aggregation occurs on cooling in methylcyclohexane-isopentane but not to a significant extent in toluene Dilute (10 μM) solutions of Chl a or Pyrochl a in nonpolar solvents form a new absorption peak near 700 nm at low temperatures, which we attribute to traces of water in the solvent or other residual nucleophiles not removed during the Chl purification Addition of stoichiometric amounts of water increases the size of the ˜700 nm peak even in dilute Chl solutions Chlorophyll a, Pyrochl a, but not pheophytin a are shown to interact with nucleophiles of the general type RXH (where R= H or alkyl, and X = O, N, or S) Such nucleophiles can coordinate to the Mg atom of one Chl molecule by lone pairs on O, N, or S, and hydrogen bond to oxygen donor functions in another Chl molecule A ˜01 M solution of Chl a or Pyrochl a in toluene containing 15 equivalents of ethanol is converted almost entirely to a species absorbing at ˜700 nm at 77 K Infrared spectroscopy shows conclusively that it is the keto C=O function that is involved in the cross-linking by hydrogen bonding, a conclusion supported by the observation that Pyrochl a forms a very similar red-shifted species at low temperatures, despite the absence of a carbomethoxy C=O function n-Butylamine and ethanethiol interact in much the same way as does ethanol to form species red shifted to ˜700 nm A variety of possible structures for the low temperature forms is discussed, and the use of these red shifted species as paradigms for photoreaction center Chl is described

Carbon, oxygen and silicon impurities in gallium arsenide

Abstract: The concentrations of carbon, oxygen and silicon, together with boron, aluminium, sulphur and potassium, in various samples of bulk gallium arsenide have been determined by spark source mass spectrometry (SSMS) calibrated by independent chemical methods. Hall effect measurements and localised vibrational mode (LVM) infrared absorption measurements have been made on the same samples. It is inferred that the carbon atoms which show LVM absorption are located on arsenic lattice sites and act as acceptors. Calibrations for the LVM lines for CAS, SiGa, AlGa and BGa have been obtained. All samples examined contained a very low concentration of oxygen in the range (1-4)*1015 cm-3. Carbon concentrations of up to 1017 cm-3 were measured in deliberately doped material, while other crystals contained levels of 5*1015 cm-3 or lower.

Vibrational spectroscopic studies of some lead silicate glasses

Abstract: Results are presented of measurements on the infrared and laser Raman spectra of some lead silicate glasses of general formula (PbO)x(SiO2)y. For the infrared spectra, the frequency dependence of the imaginary component of the complex dielectric constant was determined from a Kramers-Kronig analysis of the reflectance spectra of the glasses at normal incidence. Apparently the addition of small amounts of PbO to vitreous silica serves to modify the continuous three-dimensional silica network; whereas in those glasses with a high lead content, the influence of the cation, Pb2+, appears to lie between that of network former and network modifier.

Very Thin Silicon Nitride Films Grown by Direct Thermal Reaction with Nitrogen

Abstract: Very thin uniform silicon nitride films less than 100A have been obtained on silicon wafers by direct thermal reaction with nitrogen at temperatures ranging from 1200° to 1300°C. Small amounts of water or oxygen in reaction mixture caused vapor etching which gave rise to local crystallization. By eliminating both from the reaction ambient to less than 1 ppm, amorphous silicon nitride films can be deposited. These films have been found to have properties similar to those of CVD by investigations of Auger electron spectroscopy, infrared spectroscopy, and ellipsometry. Remarkable masking effects of the films against oxidation and phosphorus diffusion have been found.

A theoretical study of the OH stretching region of the vibrational spectrum of ice Ih

Abstract: We describe a theoretical interpretation of the OH stretching region of the vibrational spectrum of ice Ih derived from a study of extended models. The principle conclusions are the following: (i) The breadth and distribution of vibrational modes, and of intensity in the Raman and infrared spectra, are dominated by the influence of strong intermolecular coupling. The intermolecular coupling is comparable in strength to the intramolecular coupling. Long range couplings between molecules not directly hydrogen bonded mainly serve to make the features of the spectrum more diffuse than they would otherwise be, but have no great influence on the spectral distribution. (ii) The intramolecular OH stretch‐OH stretch coupling in ice Ih is of opposite sign to that in the gas phase. (iii) The vibrational modes of ice Ih are found to be complex mixtures of molecular motions, so identification of regions of the Raman or infrared spectra with particular isolated molecule modes is not useful. Rather good agreement is obtained between the Raman and infrared spectra predicted and those observed. Some deficiencies of the model, associated with residual discrepancies between theory and experiment, are discussed.

Local order as determined by electronic and vibrational spectroscopy: Amorphous semiconductors

Abstract: Raman and infrared spectroscopy yield detailed information about the vibrational modes of solids. Photoelectron spectroscopy gives corresponding information on valence and core electronic states. From these spectroscopies the nature of the local atomic order can be inferred. Applications of these methods are illustrated for prototype tetrahedral and chalcogenide amorphous semiconductors. The retention of the crystalline short range order is manifested in the vibrational spectrum of pure amorphous silicon and the III–V compounds. Similar conclusions are obtained from the photoelectron spectra along with additional information on ring configurations. For Se and chalcogenide compounds (e.g. GeTe) vibronic and electronic spectral reveal differences between amorphous and crystalline short range orders. In addition to these intrinsic structures, the local environments and effects of additives, such as hydrogen and conventional dopants in amorphous silicon, are discussed.

Infrared absorption of silicon irradiated by protons

Abstract: Hydrogen implantations into silicon samples at room temperature and at 190°C are carried out. Infrared studies are performed on these samples before and following annealing. Previously observed divacancy and hydrogen vibrational bands are found as well as higher-order-bands not previously found in proton irradiation. In addition new hydrogen vibrational bands and other bands are observed and discussed. In Siliziumproben wird Wasserstoff bei Zimmertemperatur und bei 190°C implantiert. An diesen Proben werden Infrarotuntersuchungen vor und nach Ausheilung durchgefuhrt. Es werden sowohl die fruher beobachteten Doppelleerstellen- und Wasserstoffschwingungsbanden als auch Banden hoherer Ordnungen gefunden, die fruher bei Protonenbestrahlung nicht gefunden wurden. Zusatzlich werden neue Wasserstoffschwingungsbanden und andere Banden beobachtet und diskutiert.

Vibration Spectra and Rotational Isomerism of Chain Molecules. VII. 1-Chloro-, 1-Bromo-, and 1-Iodopropanes, and 1-Chloro-, 1-Bromo-, and 1-Iodobutanes

Abstract: The Raman and infrared spectra of 1-chloro-, 1-bromo-, and 1-iodopropanes, CH3CH2CH2X (X=Cl, Br, and I), and 1-chloro-, 1-bromo-, and 1-iodobutanes, CH3CH2CH2CH2X (X=Cl, Br, and I), were measured for the gaseous, liquid, glassy, and crystalline states. The normal vibration frequencies were calculated, a consistent set of force constants explaining the frequencies of basic halogenoalkanes being assumed. The rotational isomerism was studied on the basis of the spectral observations and the normal coordinate calculations. The enthalpy differences among the rotational isomers were examined.

Adsorption of γ‐aminopropyltriethoxysilane onto bulk iron from aqueous solutions

Abstract: The adsorption of γ-aminopropyltriethoxysilane (γ-APS) onto mechanically polished iron coupons from 1% aqueous solutions has been investigated using reflection–absorption infrared spectroscopy. Thick films were formed on the coupons during 1-hr exposures to the γ-APS solutions. The outermost portion of these films consisted of highly hydrolyzed polysiloxanes that were weakly bound and easily desorbed by cold water. This fraction of the films was characterized by an infrared band near 1575 cm−1 that was tentatively assigned to the NH2 deformation of acceptor amine groups in strong hydrogen bonds or to coordination of the amino nitrogen atoms to silicon atoms. Removal of the weakly bound outermost portion of the films with water revealed an incompletely hydrolyzed, strongly bound film approximately 60 A in thickness characterized by a band near 1510 cm−1 that was assigned to NH groups. Formation of NH3+ groups indicated that γ-APS may have been adsorbed initially as cyclic, internal zwitterions.