Absorption strength measurement of the ν1 band of methyl chloride

The absorption strengths of the Q-branch manifolds of the ν₁ band of methyl chloride have been measured. The results have been used to deduce the band strength which is 32.1 ± 2.9 cm^?2 atm^?1 at 297 K. The P-branch absorptions have been investigated to determine the possibility of determining a vibration-rotation factor for the band. This factor is 1 + (2αβ + γ) ～ 1.026.     

Intensities of the v1-bands of 12CH335Cl and 12CH337Cl near 3 μm

Strengths of individual lines in the v₁ fundamental of methyl chloride have been measured at low pressure and at 296.35 K using a Fourier transform interferometer. The band strengths S_v⁰ obtained by fitting these measurements are 85.8±1.0 and 86.6±1.0 cm^-2 atm^-1 for ¹²CH₃³⁵Cl and ¹²CH₃³⁷Cl, respectively. The Q₃-branch appears to be useful for atmospheric detection of methyl chloride.     

The Enfrared Spectra of tris (Methyl Methylphosphonate) Iron(III), Tris (Ethyl Ethylphosphonate) Iron(III), and Tris (Isopropyl Methylphosphonate) Iron(III)

The literature contains few references to the reactions of phosphonate esters with iron salts. Guilbault et al. ¹ recently studied the infrared spectrs of diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DIMP) chemisorbed on solid FeCl ³ and made infrared band assignments. We wish to report the results of a study of the products of the homogeneous reaction of DIMP, DMMP and diethyl ethylphosphonate (DEEP) with ferric chloride. On the basis of elemental analysis and infrared absorption data, the products isolated were identified as tris (methylmethylphosphonate) iron (III), tris (ethyl ethylphosphonate) iron (III), and tris (isopropyl methylphosphonate) iron (III).     

The effects of internal rotation on some infrared and electronic band contours of tetrolaldehyde

Contour calculations are reported for one electronic band and three infrared bands of tetrolaldehyde, CH₃CCCHO, where the methyl group executes relatively free internal rotation with respect to the body of the molecule. The electronic band described, the 0-0 band of the π^∗ ← n transition near 3760 Å, has the transition moment located in the molecular frame. The infrared bands are the 3 degenerate perpendicular bands of the methyl group, having the transition moments localized in the rotating group. Gross differences in contour are observed in the two types of bands.     

Raman spectroscopic study of the antimonate mineral brandholzite Mg[Sb2(OH)12]·6H2O

Raman spectra of brandholzite Mg[Sb₂(OH)₁₂]·6H₂O were studied, complemented with infrared spectra, and related to the structure of the mineral. An intense Raman sharp band at 618 cm⁻¹ is attributed to the SbO symmetric stretching mode. The low‐intensity band at 730 cm⁻¹ is ascribed to the SbO antisymmetric stretching vibration. Low‐intensity Raman bands were found at 503, 526 and 578 cm⁻¹. Corresponding infrared bands were observed at 527, 600, 637, 693, 741 and 788 cm⁻¹. Four Raman bands observed at 1043, 1092, 1160 and 1189 cm⁻¹ and eight infrared bands at 963, 1027, 1055, 1075, 1108, 1128, 1156 and 1196 cm⁻¹ are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3240, 3383, 3466, 3483 and 3552 cm⁻¹; infrared bands at 3248, 3434 and 3565 cm⁻¹. The Raman bands at 3240 and 3383 cm⁻¹ and the infrared band at 3248 cm⁻¹ are assigned to water‐stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm⁻¹ and two infrared bands at 3434 and 3565 cm⁻¹ are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands in the OH stretching region are associated with O‐H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis, characterization and electrochemical behavior of polypyrrole/carbon nanotube composites using organometallic-functionalized carbon nanotubes

Thorn-like, organometallic-functionalized carbon nanotubes were successfully developed via a novel microwave hydrothermal route. The organometallic complex with methyl orange and iron (III) chloride served as reactive seed template, resulting in the oriented polymerization of pyrrole on the modified carbon nanotubes without the assistance of other oxidants. Morphological and structural characterizations of the carbon nanotube/methyl orange-iron (III) chloride and polypyrrole/carbon nanotube composites were examined using transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), infrared spectroscopy and X-ray diffraction (XRD). The electrochemical property of the polypyrrole/carbon nanotube composite was elucidated by cyclic voltammetry and galvanostatic charge-discharge. A specific capacitance of 304 F g⁻¹ was obtained within the potential range of −0.5-0.5 V in 1 M KCl solution.     

High-resolution spectrum of the ν9 band and reinvestigation of the ν8 band of cis-CH3ONO

The infrared spectrum of methyl nitrite CH₃ONO has been recorded at a spectral resolution of 0.003 cm^?1 using a Fourier-transform spectrometer Bruker IFS125HR. The ν₈ band of the cis isomer has been reinvestigated in the 780–880 cm^?1 spectral range to complete the study made by Goss et al. (2004) [3] and to fit the internal rotor splittings. The BELGI-IR program, which enables us to treat an isolated infrared band for asymmetric molecules containing one internal methyl rotor has been used for the analysis and predictions of spectra. Finally 1036 lines (913 A-type and 123 E-type lines for J≤50 and K_a≤28) have been assigned for the cis isomer and fitted with a standard deviation of 0.00047 cm^?1.Furthermore, for the first time, the ν₉ band of cis-CH₃ONO was investigated in the 540–660 cm^?1 spectral range and rather large internal rotation splittings were also observed at higher J values. For the ν₉ band, the effective approach performed with the BELGI-IR program allowed us to analyze and reproduce 682 lines up to J=50 and K_a=18 with a standard deviation of 0.00051 cm^?1. The multiple vibration–rotation–torsion interactions, which are likely to occur between the excited v₉=1 and v₈=1 states and the torsional manifolds are discussed.     

Investigation of the ν8 and ν21 bands of propane CH3CH2CH3 at 11.5 and 10.9 µm: evidence of large amplitude tunnelling effects

ABSTRACT

We present the first investigation of the ν₈ band (C–C symmetric stretch at 870.3137?cm^?1), together with an extended analysis of the neighbouring ν₂₁ band (CH₃ rock at 921.3756?cm^?1) of propane (C₃H₈). Our previous investigation of the ν₂₁ A-type band [A.Perrin, F. Kwabia-Tchana, J.M.Flaud, L.Manceron, P.Groner, W.J.Lafferty. J. Mol. Spectrosc. 315, 55 (2015)] revealed that the rotational energy levels of 21¹ are split because of interactions with the internal rotations of the methyl groups, leading to the identification of AA, EE, AE and EA torsional components. In this work, a similar behaviour was observed for the B-type ν₈ band and the analysis of the ν₂₁ band was greatly extended. One of the results of the present study is to show that these torsional splittings are due to the existence of anharmonic and Coriolis resonances, coupling the 21¹ and 8¹ rotational levels to nearby highly excited levels of the two internal rotations of the methyl groups. Accordingly, an effective ‘vibration – torsion- rotation’ Hamiltonian model was built in the G₃₆ symmetry group which accounts for both types of resonances. In parallel, a code computing the line intensities was developed to allow unambiguous torsional component assignments. The line assignments were performed using a high resolution (0.0015?cm^?1) infrared spectrum of propane, recorded with synchrotron radiation at the SOLEIL French light source facility coupled to a Bruker IFS-125 Fourier transform spectrometer. Finally, a linelist of positions and intensities which can be used for the detection of propane in the Earth and outer planets atmospheres was produced.     

Raman spectroscopic study of the antimonate mineral bottinoite Ni[Sb2(OH)12]·6H2O and in comparison with brandholzite Mg[Sb5+2(OH)12]·6H2O

Raman spectroscopy was used to study the mineral bottinoite and a comparison with the Raman spectra of brandholzite was made. An intense sharp Raman band at 618 cm⁻¹ is attributed to the SbO symmetric stretching mode. The low intensity band at 735 cm⁻¹ is ascribed to the SbO antisymmetric stretching vibration. Low intensity Raman bands were found at 501, 516 and 578 cm⁻¹. Four Raman bands observed at 1045, 1080, 1111 and 1163 cm⁻¹ are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3223, 3228, 3368, 3291, 3458 and 3510 cm⁻¹. The first two Raman bands are assigned to water stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm⁻¹ and two infrared bands at 3434 and 3565 cm⁻¹ are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands are connected with O H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2010 John Wiley & Sons, Ltd.     

Infrared evidence for the folded-chain model of trans-1,4-polybutadiene

The influence of the first-order crystalline transformation at about 60°C on the infrared bands of trans-1,4-polybutadiene yields microscopic information that supports the two-component microcrystalline model of a folded chain having loose and tight end loops at the lamellar surfaces. The temperature dependence of the band parameters of the 908-cm^?1 vinyl band indicates that 1,2-(side vinyl) units are not easily taken into the crystalline component, thus forming long loops at the crystal surface that account for the micro-Brownian motion detected in the low-temperature phase. The results argue that infrared band parameters are excellent probes for details of the thermodynamics and morphology of polymers.     

Experimental development of reflection-absorption spectroscopy: Infrared spectrum of carbon monoxide adsorbed on copper and copper oxide

The reflection-adsorption technique is used to obtain the infrared spectrum of a monolayer or less of carbon monoxide adsorbed on an evaporated copper film. The band is located at 2105 cm⁻¹ and is obtained with a signal-to-noise ratio in the range 5 to 15. In this technique, the infrared beam is multiply reflected between two closely-spaced parallel metal surfaces covered with the adsorbed layer. The CO band is used to investigate the dependence of the signal-to-noise ratio on the spacing of the metal surfaces. The existence of an optimum value of the spacing is demonstrated. The contribution to the absorption band of infrared rays with different angles of incidence is investigated and explained in terms of an optimum number of reflections and its variations with angle of incidence. After the copper surface is progressively exposed to oxygen, a slight shifting of the CO band to 2113 cm⁻¹ is observed. Further exposure gives rise to a new band of adsorbed CO at 2135 cm⁻¹, interpreted as CO adsorbed on copper oxide.     

Raman and infrared spectra of the all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers of β-carotene: Key bands distinguishing stretched or terminal-bent configurations form central-bent configurations

Raman and infrared spectra in the region of 1800-150 cm⁻¹ were recorded for a set of cis-trans isomers of d̃-carotene, i.e. the all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers. Spectral comparison revealed Raman and infrared key bands which (1) distinguish stretched or terminal-bent configurations (all-trans, 7-cis and 9-cis) from central-bent configurations (13-cis and 15-cis), and (2) distinguish unmethylated 7-cis and 15-cis configuratios. Keybands (1) include Raman bands at 1160 and 1140 cm⁻¹ and infrared bands at 825 and 775 cm⁻¹ (the intensity varies with the position of the cis-bend) Key bands (2) include Raman bands at 1274 and 962 cm⁻¹ and an infrared band at 741 cm⁻¹ (characteristic of the 7-cis configuration), and also a Raman band at 1247 cm⁻¹ and an infrared band at 775 cm⁻¹ (characteristic of the 15-cis configuration). The normal modes for the key bands were determined by a set of normal coordinate calculations for the isomeric configurations of a simplified model of d̃-carotene. The key bands were mainly related to the C H in-plane bendings, coupled with the CC or C C stretching, or to the C H out-of-plane wagging vibrations, some of which coupled with the CC torsion.     

Adsorption d'hydrogène entre 300 et 873 K sur un catalyseur Pt/MgO

Hydrogen adsorption on MgO-supported platinum was studied by thermal desorption and infrared spectroscopy at 300 and 800 K. For both temperatures, reversibly and irreversibly adsorbed species have been detected. At 300 K, reversible adsorption leads to the appearance of infrared bands at 2120 and 2060 cm^?1, attributed to terminal Pt-H species. Irreversibly adsorbed hydrogen has been detected by thermal desorption, whereas no infrared band was detected in the spectral range 4000–4750 cm^?1 for Pt/MgO sample. For hydrogen adsorption at 800 K, reversibly adsorbed hydrogen gave the same picture as for the 300 K adsorption. An additional form of irreversibly adsorbed hydrogen has been evidenced both by thermal desorption and infrared spectroscopy. This form corresponds to hydrogen strongly adsorbed on platinum and gives an infrared band at 950 cm^?1 which is characteristic of an hydrogen atom in interaction with more than one platinum atom (multicentered) species.     

The Rydberg spectroscopy of methyl chloride

The absorption spectrum of methyl chloride has been studied in the energy region from 68 600 to 94 760 cm^?1. With the exception of a valence-shell transition, all transitions were interpreted as molecular Rydberg transitions. These assignments were made utilizing the Rydberg formula. The similarity of the vibrational fine structures observed in the photo-electron spectrum of methyl chloride and its VUV spectroscopy is shown to further support the Rydberg assignments.     

Vibrational spectroscopic characterization of the magnesium borate-phosphate mineral lüneburgite

ABSTRACT

Lüneburgite, a rare magnesium borate-phosphate mineral from Mejillones, Chile, has been characterized using Raman and mid-infrared spectroscopy methods. Boron tetrahedra are characterized by sharp Raman band at 877?cm^?1, attributed to the ν₁[BO₄]^5? symmetric stretching mode. The phosphate anion is associated with a distinct band at 1032?cm^?1, attributed to the ν₃[PO₄]^3? antisymmetric stretching mode. The most intensive Raman band at 734?cm^?1 is ascribed to stretching vibrations of bridging oxygen atoms in boron–oxygen–phosphor bridges. Bonds associated with water bending mode and stretching vibration are observed at 1661?cm^?1 (infrared) and in the 3000–3500?cm^?1 region (Raman and infrared spectrum).     

A high-resolution study of the ν7 band of propyne

The infrared spectrum of propyne (methyl acetylene) between 1300 and 1620 cm^?1 has been reanalyzed at a resolution of 0.006 cm^?1. The main Fermi and Coriolis interactions of the ν₇^±1 band have been identified, as has the Fermi interaction between (ν₈ + ν₁₀)⁰ and ν₄⁰. Reassignment of a subband shows that ν₄⁰ has a very small transition moment. Thirty-eight molecular parameters for the interacting excited vibrational levels were determined by a least-squares analysis of 1550 lines.     

Far Infrared Spectroscopic Studies of Acetonitrile Vapour

Abstract

The infrared spectrum of acetonitrile vapour has been obtained in the range below 100 cm^?1. There is an absorption band located at 78 cm^?1 which is assigned to overlapping intermolecular vibrations of dimer molecules in equilibrium with the monomer species. The equilibrium constant calculated from the pressure dependence of the band intensity amounts to 42 ± 26 1·mol^?1.     

Mid-infrared absorption cross-sections and temperature dependence of CFC-113

The temperature dependence of the infrared absorption cross-sections of CFC-113 (1,1,2-trichlorotrifluoroethane) in a pure vapor phase has been recorded in the 600-1250 cm⁻¹ spectral region using Fourier transform spectroscopy. Spectra at 0.05 cm⁻¹ resolution have been used to derive the integrated band strengths of the five main absorption bands over a range of temperatures from 223 to 283 K. Our results show good agreement with previously published data. The new cross-sections will allow more accurate retrieval of atmospheric CFC-113 concentrations using infrared spectroscopic techniques.     

SiCl bonds in α-Si:H:Cl films

The infrared and Raman spectra of α-Si:H:Cl films prepared by glow discharge were measured. The dependence of SiCl bonds on the preparation conditions of films was investigated. The results show that chlorine is incorporated only in monochloride bonding geometry at higher substrated temperature (400 C). And SiCl₂ bonds were also formed at lower substrate temperature (200–300 C). The band at 795 cm⁻¹ is related to the incorporation of oxygen and hydrogen rather than that of chlorine.     

Temperature evaluation of UF6 and cluster detection in nozzle expansion using low-resolution infrared absorption spectroscopy

6 and mixtures of UF₆ with argon and nitrogen through a bidimensional nozzle was studied using low-resolution infrared spectroscopy in the ν₃ absorption band region. The experiments were carried out in order to calculate the molecular temperature of the beam and also to verify cluster formation in the expansion. The molecular beam temperature evaluation was based on the measurements of the low-resolution bandwidth, which were compared to simulated spectra results. The temperatures were also evaluated using the measured pressure at the end of the nozzle by a pitot tube. In the conditions where no cluster formation was observed the calculated theoretical temperatures using an equilibrium expansion model are in good agreement with the data obtained through the analysis of the experimental spectra and through the pitot tube pressure measurement. Cluster formation was observed for temperatures below about 120 K. In these conditions the infrared spectra showed shoulders in the region above 630 cm^-1 and a shoulder or band between 616 and 600 cm^-1. Received: 5 January 1998/Accepted: 14 May 1998