Showing papers on "Infrared spectroscopy published in 1969"
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31 Dec 1969
TL;DR: In this article, the authors proposed a structure elucidation by joint application of UV and nuclear magnetic resonance spectra (NMRS) for visible and visible spectra, respectively, in the presence of UV.
Abstract: Ultraviolet and Visible Spectra. Infrared Spectra. Nuclear Magnetic Resonance Spectra. Mass Spectra. Structure Elucidation by Joint Application of UV
1,895 citations
TL;DR: In this paper, a tentative assignment for the hydrocarbon flame bands has been proposed which is in reasonable agreement with the observed band structure of the emission system, in contrast to the results of previous studies.
Abstract: The photoproduction of H or D atoms from a variety of sources in a carbon monoxide matrix or in an argon matrix to which a small concentration of carbon monoxide has been added leads to the appearance of prominent ultraviolet absorptions between 2100 and 2600 A, all of which may be assigned to HCO or DCO. Both the CO‐stretching and the bending vibrational modes are appreciably excited in the transition. Evidence is presented indicating that the transition observed in the matrix experiments is the same one responsible for the hydrocarbon flame bands. Using the frequencies observed in the matrix experiments, a tentative assignment for the hydrocarbon flame bands has been proposed which is in reasonable agreement with the observed band structure of the emission system. In the upper state, the carbon and oxygen atoms of HCO are approximately singly bonded. Observation of the infrared absorption frequencies of isotopically substituted HCO in an argon matrix has prompted reconsideration of the valence force field appropriate to ground‐state HCO. Interaction between the CH‐stretching and the CO‐stretching modes has been found to play an important role. Factors leading to the stabilization of HCO in an argon matrix in the present experiments, in contrast to the results of previous studies, are discussed.
163 citations
TL;DR: In this article, it was shown that the isotope effect is as large as in the system HCrO2-DCrO2, and that the O O distance of HCoCO2 is 2.57(2) A.
Abstract: Cobaltic acid, HCoO2, and deuterated cobaltic acid, DCoO2, have been prepared and studied by x‐ray and neutron‐diffraction techniques, and by infrared spectroscopy and cold‐neutron scattering. The materials crystallize in apparent space group D3d5–R<3¯m of the trigonal system with three molecules in a hexagonal cell of dimensions: HCoO2, a = 2.851(1), c = 13.150(5) A; DCoO2, a = 2.854(1), c = 13.354(5) A. The O–O distance, as determined by neutron‐powder studies, of HCoCO2 is 2.50(2) A. On this basis and the fact that there are three O–H–O bonds along the c direction, the O–D–O distance is 2.57(2) A. Hence, the isotope effect here is as large as in the system HCrO2–DCrO2. Infrared studies at room temperature and at − 195°C over the region 70–4000 cm−1 may be interpreted in terms of an effectively symmetric O–H–O bond and an effectively asymmetric O–D–O bond. Although the neutron inelastic scattering measurements are not inconsistent with this interpretation, there is a band centered at 264 cm−1 in the neutron spectrum for HCoC2, which is not observed in the infrared spectrum. Model calculations, based on a two‐dimensional potential function in which the asymmetric stretching frequency is coupled to the symmetric stretching frequency, were unsuccessful owing to the magnitude of the coupling term required to account for the very large isotope effect.
132 citations
TL;DR: In this paper, the inplane vibrations of the X2Y2(Vh) ring and the X3Y3(D3h) rings were modeled using 18O substitution, and it was shown that these respective models account for the observed ir absorptions of Si2O2 and Si3O3.
Abstract: The matrix isolation of silicon monoxide vapor leads to the formation of at least three distinct species: SiO, Si2O2, and Si3O3. Infrared absorptions for these molecules are observed at 1223.9 cm−1 (Si16O); 804.7, 766.3 cm−1 (Si216O2); 972.6, 631.5, 312.0 cm−1 (Si316O3). Equations are given for the in‐plane vibrations of the X2Y2(Vh) ring and the X3Y3(D3h) ring, and using 18O substitution, it is shown that these respective models account for the observed ir absorptions of Si2O2 and Si3O3. Estimates are given for the molecular dimensions of Si2O2 (rSi–O = 1.71 A, ∠OSiO = 87°) and Si3O3 (RSi–O = 1.70 A, ∠OSiO = 100°), and for their unobserved vibration frequencies. The reaction SiO + Si2O2 → Si3O3 is observed during diffusion studies, and a lower limit obtained for the mean bond energy in Si3O3 of ∼104 kcal/mole.
129 citations
TL;DR: In this article, the technique of Raman spectroscopy can be used to the problem of the identification of minerals and can, in certain circumstances, provide some structural information The method can also be used for a wide variety of minerals, though the results only for those containing MO3 or MO4 functional groups (carbonates, silicates, phosphates, arsenates, vanadates, sulphates, chromates, molybdates, tungstates).
Abstract: I WISH to show that the technique of Raman spectroscopy can be usefully applied to the problem of the identification of minerals and can, in certain circumstances, provide some structural information The method can be used for a wide variety of minerals, though here I report results only for those containing MO3 or MO4 functional groups (carbonates, silicates, phosphates, arsenates, vanadates, sulphates, chromates, molybdates, tungstates) Although infrared spectra of minerals have long been studied1 there have been no systematic Raman studies apart from some very early work on silicates and sulphates2; there are some elegant studies on single crystals of a few specific minerals such as barytes3, gypsum4 and quartz5 All the minerals studied here have known structures or known lattice space groups, and in most cases infrared data are available for them; thus there are two checks on the interpretation of Raman spectra It must be emphasized that Raman and infrared spectroscopy are complementary techniques and should, wherever possible, be used together, though valuable information may be derived from the use of one method alone
107 citations
TL;DR: The multiple maxima in the spectra of hydrogen-bonded systems are caused by Fermi resonance of νOH(broad band) with 2δOH and 2γOH such that the minima correspond to the overtone frequencies.
Abstract: The multiple maxima in “A,B,C”-type i.r. spectra of hydrogen-bonded systems are caused by Fermi resonance of νOH(broad band) with 2δOH and 2γOH such that the minima correspond to the overtone frequencies.
107 citations
TL;DR: In this paper, the external optical phonon modes in the ammonium and deuteroammonium halides have been studied through their intrinsic phase transitions in the temperature range 4 −290°K using infrared and Raman techniques.
Abstract: The external optical phonon modes in the ammonium and deuteroammonium halides have been studied through their intrinsic phase transitions in the temperature range 4–290°K using infrared and Raman techniques. The number of infrared and Raman active modes are in agreement with group theoretical predictions for the phases II, III, and IV, with the exception that no measurable anisotropic splitting of the out‐of‐phase mode in the tetragonal phase was observed in the infrared spectra. Whilst the frequency of the infrared reststrahlen modes showed only small discontinuities with temperature as the phase transitions were traversed, the phonon lifetimes of these modes showed distinct increases as the temperature was lowered through each phase transition. Estimates of the intrinsic ionic distortion present in NH4Cl and NH4Br are given. The compressibilities of NH4Cl and NH4Br at 4°K are calculated to be 3.86 × 10−12 and 6.79 × 10−12 cm2 dyn−1.
107 citations
TL;DR: In this article, the infrared absorption of poly(ethylene glycol) was measured in the molten state, and the properties of the infrared bands and Raman lines were identified based on potential energy distributions.
Abstract: The infrared absorption of poly(ethylene glycol) was measured in the molten state. Characteristic bands of the molten state were identified. Normal vibrations and frequency distributions were treated for various conformation models with CH2CH2O repeat units. The infrared absorption peaks of the molten state closely correspond to the frequency distribution peaks of the TGT conformation with gauche OCH2CH2O groups, although infrared bands due to trans OCH2CH2O groups are also observed. Vibrational assignments of the infrared bands and Raman lines were made on the basis of potential energy distributions.
102 citations
101 citations
TL;DR: In this paper, the infrared absorption spectra of photolyzed Ar:CF3F samples include bands which may be assigned to CH, to CF, and to HCF.
Abstract: Upon vacuum‐ultraviolet photolysis of methyl fluoride in an argon or a nitrogen matrix at 14°K, the free radicals CF, HCF, and H2CF are stabilized in sufficient concentration for observation of their infrared absorption spectra. Studies utilizing carbon‐13 and deuterium substitution confirm the identification of these species. Visible‐ultraviolet absorption spectra of photolyzed Ar:CF3F samples include bands which may be assigned to CH, to CF, and to HCF. The reaction of carbon atoms, produced by the photolysis of cyanogen azide isolated in an argon matrix, with HF trapped in the matrix has also been found to lead to the stabilization of sufficient HCF for infrared spectroscopic detection. Reaction of HCF with a second molecule of HF to form CH2F2 also occurs. The force constants and thermodynamic properties of HCF have been calculated, and a partial vibrational assignment is proposed for H2CF. Although these experiments do not determine the primary photodecomposition processes important for methyl fluoride, there is evidence that both H atom and F atom detachment may occur under the conditions of these experiments.
TL;DR: In this paper, the Raman spectra of aqueous solution of barium trifluoromethanesulfonate and sodium trichloromethane sulfonate including qualitative polarization measurements together with the infrared spectra have been recorded.
TL;DR: In this paper, the fundamental frequencies of isotopically dilute H2O, D2O and HDO molecules were obtained from the infrared spectra of partially deuterated hydrates.
Abstract: Infrared spectra of partially deuterated hydrates yield the fundamental frequencies of isotopically dilute H2O, D2O, and HDO molecules. Isotopic dilution eliminates vibrational coupling and allows ...
TL;DR: In this article, the infrared spectra of binary oxides of the types RE 2 Ti 2 O 7, RE 2 Zr 2 O7, and RE 2 Hf 1 O 7 were used to distinguish between ordered and disordered structures of pyrochlore type compounds.
TL;DR: The infrared absorption spectra of gaseous 2,5,dihydrofuran, 3,oxetanone, 2,methyl-4,5-dimethyl-dimethylamino-dioxene, cyclopentanone and cyclohexanone have been observed in the range 250-25 cm−1 as mentioned in this paper.
Abstract: The infrared absorption spectra of gaseous 2,5‐dihydrofuran, 3‐oxetanone, 2‐methyl‐4,5‐dihydrofuran, diketene, cyclopentanone, and cyclohexanone have been observed in the range 250–25 cm−1. Under high resolution the spectrum of 2,5‐dihydrofuran shows a satellite series of Q branches in addition to those observed by Shimanouchi and Ueda. The satellites arise from transitions between ring‐puckering energy levels in an excited ring‐twisting state with altered spacing due to higher‐order cross terms in the potential energy. The spectrum of 3‐oxetanone is that of a planar molecule, and the energy levels of the ring‐puckering mode fit a potential function of the form V(x) = ax4 + bx2. The absorption of 2‐methyl‐4,5‐dihydrofuran is complicated by several low‐frequency modes, but the spectrum can be fairly well interpreted with a double‐minimum potential function of the form V(x) = ax4−bx2 with a barrier height of 98 cm−1. Seven sharp Q branches were observed for cyclopentanone, which were fitted to a hindered ps...
TL;DR: In this article, the IR spectra of Linde X- and Y- type zeolites, charge-balanced with different monovalent and divalent cations, were examined in the OH and NH regions after evacuation at various temperatures and when H 2 O or NH 3 was added back.
TL;DR: In this article, the infrared spectra of gaseous trimethylenimine and 2,5dihydropyrrole and the oxygen atom of cyclopentene oxide have been observed in the range 300-25 cm−1.
Abstract: The infrared spectra of gaseous trimethylenimine, trimethylenimine‐N‐d, 2,5‐dihydropyrrole, 2,5‐dihydropyrrole‐N‐d, and cyclopentene oxide have been observed in the range 300–25 cm−1. The N–H bonds of trimethylenimine and 2,5‐dihydropyrrole and the oxygen atom of cyclopentene oxide introduce asymmetry into the potential function for inversion of the ring in these molecules. In consequence the eigenvalues of the inversion vibrations are quite irregular but can be inferred from the spectra and fitted to a potential function of the form V(x) = ax4 − bx2 + cx3, where x is the ring‐inversion coordinate. Interpretation of the far‐infrared spectrum also enables assignment of the satellite fine structure of certain of the mid‐infrared fundamentals as difference bands involving the inversion vibration.
TL;DR: In this paper, Raman and infrared spectra have been obtained for K[PtCl3(C2H4)]·H2O (Zeise's salt), K[pCl3[C2D4]·H 2O, and [ptCl2[C 2H4]2]2.
TL;DR: A review of stellar spectroscopy can be found in this article, where the authors focus on the stellar spectra, rather than the problems and triumphs of instrumental technique, and their focus is restricted to stars and to wavelengths longer than 9000 A (0.9 p).
Abstract: This review of infr·ared spectroscopy will be restricted to stars, and to wavelengths longer than 9000 A (0.9 p.). Infrared studies of the Sun will not be considered for their own sake but will frequently be called upon to help interpret the spectra of other stars. Infrared stellar photometry will be discussed only when it can be used to study spectral features. Finally, our concern wiII be the stellar spectra, rather than the problems and triumphs of instrumental technique. According to the terminology now in fairly general use, the infrared is divided into the following four regions: the near infrared, roughly 0.7-0.9 po, invisible to the eye but accessible to the N-type photographic emulsion; the one-micron region, roughly 0.9-1 . 1 p., accessible to the Z emulsion and to S1 photocathodes; the two-micron region, roughly 1.2-2.5 J.L, in which PbS photoconductive cells are often used (hence sometimes called the "lead sulfide region") i and the far infrared, extending from about 3 p. to millimeter wavelengths and the domain of radio astronomy. These regions are quite distinct to an infrared observer; the completeness of our knowledge of stel lar spectra drops sharply from region to region toward longer wavelengths but is fairly uniform within each region. By omitting the vast quantity of material accumulated with N plates in the near infrared-which, by virtue of its relative completeness, belongs perhaps more properly in a general review of stellar spectroscopy-we can give a fairly comprehensive account of the work done at longer wavelengths. In the 1 J.I region, the identifications of spectral-features are now in a satisfactory state for G, K, and M stars, and several results of astrophysical interest have been obtained; in the 2 J.L region, important studies of molecular bands have. been made but the work on atomic-line identification is just beginning ; in the far infrared, very few spectral features have yet been detected. Infrared spectroscopy is a young field which seems now to be entering a stage of rapid development, and we have depended rather heavily upon unpublished material. There are many reasons for observing stellar spectra in the infrared, despite the difficulties imposed by low detector sensitivity and atmospheric absorption. The abundant molecules Hz, CO, and H20 can be observed only in the infrared, while some other molecules (e.g. VO and CN) and atoms
TL;DR: The Nimbus III satellite carries the satellite infrared spectrometer (SIRS), which measures the radiance of the earth and the atmosphere in seven narrow spectral intervals in the 15-micrometer carbon dioxide band and in one interval of minimum absorption at 11.1 micrometers.
Abstract: The Nimbus III satellite carries the satellite infrared spectrometer (SIRS) It measures the radiance of the earth and the atmosphere in seven narrow spectral intervals in the 15-micrometer carbon dioxide band and in one interval of minimum absorption at 111 micrometers Seven simultaneous equations are solved to obtain the vertical temperature profile; the eighth measurement is used to determine the boundary condition (cloud or surface temperature) Results agree with those obtained from conventional radiosondes
TL;DR: In this article, fractional crystallization was used to separate a commercial, predominantly isotactic, unstabilized polypropylene into fractions of relatively low and relatively high atacticity, but of similar molecular weight.
Abstract: : Fractional crystallization was used to separate a commercial, predominantly isotactic, unstabilized polypropylene into fractions of relatively low and relatively high atacticity, but of similar molecular weight. IR spectroscopy was used to follow the photo-oxidations of films formed from these fractions during irradiation in air with light of wavelengths greater than 3000 A. The major oxidation products included hydrogen-bonded hydroperoxides and carbonyl compounds. Films of constant tacticity, but varying morphology were prepared by quenching from the melt. No distinct correlation was found between sample photostability and morphology, as indicated by film density. Films of low atactic content were found to undergo faster photo-oxidation than films of high atactic content, irradiated under identical conditions. This effect is believed to be due to the occurrence of a stereo-dependnt step (or steps) in the oxidative chain, and not due to differences in sampling morphology. The possible nature of the stereo-dependent steps is considered in terms of well-established oxidative chain processes. The effects of polypropylene polymorphism on oxygen permeability are briefly considered. (Author)
TL;DR: The infrared spectrum of N,N-dimethyldithiocarbamate complex of nickel(II) has been recorded in the range 2000-250 cm−1 as discussed by the authors.
Abstract: The infrared spectrum of N,N-dimethyldithiocarbamate complex of nickel(II) has been recorded in the range 2000–250 cm−1. Normal coordinate analyses have been made for nickel dimethyldithiocarbamate and nickel dimethyldiselenocarbamate complexes and their infrared spectra indexed. The frequency shifts observed on alkyl substitution have been discussed. The M—Se stretching frequency occurs about 100 cm−1 lower in the diselenocarbamate complex as compared to M—S frequency of the dithiocarbamate.
TL;DR: In this article, the interaction of carbon dioxide with γ-alumina has been studied by infrared spectroscopy and four different adsorbed species have been observed and firm assignments made for three of them.
Abstract: The interaction of carbon dioxide with γ-alumina has been studied by infrared spectroscopy. Four different adsorbed species have been observed and firm assignments made for three of them. Absorption near 1800 cm.–1 may be due to a weakly held form of carbon dioxide, adsorbed directly on aluminium cation sites. The other species are physically adsorbed carbon dioxide (2346–2367 cm.–1), bicarbonate groups (3605, 1640, 1480, and 1233 cm.–1), and a bridged structure (1850 and 1180 cm.–1). A reaction scheme showing the relationship between these species is proposed.
TL;DR: In this article, a study of the structures of hydrated and anhydrous lanthanide acetates by X-ray diffraction, infrared spectra, and absorption spectra is presented.
TL;DR: In this article, the authors investigated the absorption spectra of MgO powders obtained from three sources and interpreted in terms of both Fr\"ohlich-type (surface) modes and classical electromagnetic scattering theory.
Abstract: Magnesium oxide powders obtained from three sources exhibit strikingly different infrared absorption spectra. These differences are correlated herein with variations in the size and shape of the particles in the powders, and are interpreted in terms of both Fr\"ohlich-type (surface) modes and classical electromagnetic scattering theory. (1) Reagent-grade MgO powder exhibits a strong and broad absorption centered at 550 ${\mathrm{cm}}^{\ensuremath{-}1}$, the position of which is determined by the Fr\"ohlich-type fundamental frequency for spherical particles that are small compared with the radiation wavelength. The absorption broadening results from variations in particle size and shape. The presence of double particles gives rise to a secondary absorption near 460 ${\mathrm{cm}}^{\ensuremath{-}1}$. (2) MgO smoke in various matrices absorbs strongly at the bulk-mode frequency (401 ${\mathrm{cm}}^{\ensuremath{-}1}$) owing to the presence of both individual large cubical particles and long chains of small cubical particles. A second strong absorption occurs at 490 ${\mathrm{cm}}^{\ensuremath{-}1}$ in Nujol, or at 546 ${\mathrm{cm}}^{\ensuremath{-}1}$ on polyethylene plates; these frequencies represent a surface mode of small MgO cubes. A shoulder at still higher frequencies is ascribed to surface modes of rod-shaped particles. (3) MgO powder obtained from thermally decomposed MgC${\mathrm{O}}_{3}$ absorbs strongly at the bulk-mode frequency (401 ${\mathrm{cm}}^{\ensuremath{-}1}$), because of the presence of large flakelike particles having a very fine grain structure. With increasing grain size, the principal absorption shifts to lower frequencies, and a secondary absorption, near 490 ${\mathrm{cm}}^{\ensuremath{-}1}$ in Nujol, appears as a result of absorption by small MgO particles.