Infrared and polarized raman spectra of kainite

The i.r. and Raman spectra of KMgClSO₄·3H₂O and its deuterated compound KMgClSO₄·3D₂O have been recorded and analysed. Due to site symmetry effects the i.r. inactive modes appear as sharp bands in the i.r. spectrum. Water bands indicate strong hydrogen bonding and show the presence of three crystallographically distinct water molecules in the unit cell.     

Infrared spectra of nitric oxide adsorbed on cobalt-alumina catalyst

Nitric oxide adsorption on the surface of a Co–Al catalyst was investigated using infrared technique. The presence of two kinds of adsorbed species was confirmed by N–O stretching frequencies at 1780 and 1855 cm^–1. The effect of potassium added to the Co–Al catalyst was examined.

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Co–Al . N–O : 1780 1855 ^–1. , Co–Al.

     

Infrared and raman spectra of crystalline quinuclidin-3-one hemiperchlorate with symmetrical NHN hydrogen bonds

Infrared and Raman studies have been performed on polycrystalline and monocrystalline samples of quinuclidin-3-one hemipercholate which at low temperature contain symmetric [NHN]⁺ hydrogen bonds. The most characteristic feature of the IR spectrum is a continuous broad absorption polarized parallel to the hydrogen bond direction.The Evans holes in the low-frequency range are most probably due to the coupling of protonic vibrations with internal modes of quinuclidine moieties leading to a modulation of the bridge geometry. Unusual isotopic and temperature effects could indicate a particular shape of the potential for the proton motion.     

2,2,2-三氯乙基·甲基醚的红外和Raman光谱及其振动归属

本文给出了2,2,2-三氯乙基·甲基醚的红外(3500-40cm^-1)和Raman(3500-50'^-1)光谱以及液相Raman谱退偏比的首次实验数据。利用修正价力场的正则坐标计算完成了两种构型的正则模式和势能分布的计算,从而做出频率的振动归属。由红外谱线606(反式)和573cm^-1(旁式)相对强随温度变化的关系求出平均热函差为161±11cm^-1(1922±134J/mol),证明两种构型中反式较旁式稳定。     

Infrared and raman spectra,conformation and force field of 3-methoxy propyne

The infrared spectra of 3-methoxy propyne (CH₃OCH₂CsolutionCH) in and in the crystalline and vapour states have been studied. The Raman spectra of 3-methoxy propyne and 3-methoxy propyne- 1-d have also been measured. The spectra are relatively simple, and no significant spectral alterations are revealed on conversion from vapour, to liquid, to the crystalline state. Together with vapour phase band contours and Raman polarization measurements this indicates that there is predominantly one conformer in all three states. An assignment has been proposed, based on a gauche conformation and supported by normal coordinate analysis.     

Infrared spectra and rotational isomerism of certain crystalline vinyl ethers

Conclusions In contrast to conformationally inhomogeneous liquid vinyl ethers, crystalline trialkylvinyloxyalkylammonium salts, according to the data of IR spectroscopy, exist practically only in the form of a flat (conjugated) conformation. An exception is trimethylvinyloxyethylammonium bromide, which crystallizes almost exclusively in a nonplanar form.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1457–1460, July, 1971.     

Infrared and Raman spectra of crystalline para-bromoaniline at low temperatures

The polarization characteristics of the i.r. absorption bands of oriented p-bromoaniline crystal films have been studied at low temperatures. Raman spectra of this compound in solution and in the polycrystalline state have been recorded as an aid to the vibrational assignment of the crystal bands. The vibrational spectra are interpreted to deduce the crystal factor group (D_2h) and the molecular site symmetry (C_s). The observed factor group splittings and dichroic ratios suggest the crystal unit cell of p-bromoaniline to be isostructural with that of p-chloroaniline.     

Low frequency vibrations in crystalline biphenyl: Model calculations and raman and neutron spectra

Vibrational frequencies of crystalline biphenyl have been calculated in the rigid phenyl approximation using the crystal structure at 110 K. The calculated results explain successfully the experimental infrared and Raman frequencies as well as the polarization data of the Raman bands at 80 K that have been observed in the present study for the first time. The frequency dispersion curves calculated in the b^* direction show that the coupling between the intramolecular CC torsion and the translational lattice vibrations changes drastically as the wave vector changes. The existence of a minimum frequency point located away from the Brillouin zone boundary indicates that the pulse transition near 40 K is a commensurate—incommensurate one in accordance with the results of neutron diffraction that have recently been reported. Incoherent inelastic neutron scattering spectra have also been investigated above and below the phase transition temperature.     

Infrared spectra of crystalline ethylenedinitramine and tetramethylenedinitramine and their N-deuterated analogs

Conclusions The IR spectra of cyrstalline ethylenedinitramine, tetramethylenedinitramine, and their deuterated deriyatives were obtained. The assignment of the frequencies for the NH valence and deformation vibrations was made.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 432–434, February, 1968.     

Infrared spectra of surface hydroxyl groups and crystalline structure of oxides

An interpretation of the infrared spectra of surface hydroxyl groups based on crystal structure considerations has been suggested for a large number of oxides. The free hydroxyl groups proved to be of several distinct types, the number of which depends on the oxygen coordination in the bulk lattice. Such an approach gives an understanding of certain properties of surface hydroxyl species, and it can be used for the interpretation of spectra of some other functional groups.     

Infrared spectra of nitric oxide adsorbed on photoreduced V/SiO2 catalyst

Studies of the IR spectra of surface species produced via NO adsorption on selectively photoreduced V/SiO₂ catalysts indicate that at low coverages NO is adsorbed on V³⁺ ions to form strongly bonded mononitrosyl species V³⁺...... NO. With increasing NO coverage, V³⁺ is oxidized to V⁴⁺, which is accompanied by the appearance of gaseous N₂O and weak adsorption of NO on V⁴⁺.

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- , NO V/SiO₂ . , V³⁺ NO V³⁺... NO. V³⁺ V⁴⁺, N₂O NO V⁴⁺.

     

Infrared and raman spectra of methyl thiocyanate and conformations of some alkyl thiocyanates and isothiocyanates

The infrared spectra (3200-40 cm^?) of gaseous and solid methylthiocyanate and the Raman spectra (3200-10 cm^?) of the liquid and solid have been recorded. A complete vibrational assignment is presented based on group frequencies, infrared gas phase band contours, and Raman depolarization values. From the infrared and Raman spectra of the solid, it is clear that there are at least two molecules per primitive cell. The spectral results will be discussed and compared to other alkyl thiocyanates and isothiocyanates.     

Infrared and raman spectra,vibrational assignment and barriers to internal rotation for methyldisilylamine

The Raman spectra of gaseous and liquid (SiH₃)₂NCH₃ and (SiH₃)₂NCD₃ have been recorded to within 10 cm^?1 of the exciting line. The IR spectra of (SiH₃)₂NCH₃ and (SiH₃)₂NCD₃ have been recorded from 80 cm^?1 to 3800 cm^?1 in the gaseous state, and from 80 cm^?1 to 450 cm^?1 in the solid state. A vibrational assignment has been made, and from the low-frequency vibrational data, an upper limit of 3.3 kcal mol^?1 was calculated for the barrier to internal rotation of the silyi groups, whereas a barrier of ~450 cal was calculated for internal rotation of the methyl group. It is concluded that there exists a significantly strong d_π—p_π interaction in methyldisilylamine.     

Infrared intensities of the external modes of crystalline nitrous oxide

The absorption intensities of two infrared active lattice modes of crystalline N₂O have been measured. Both the frequencies and intensities of the external modes of N₂O have been found to be very similar to those of CO₂, and most of the differences between the spectra of CO₂ and N₂O can be explained by the differences in the quadrupole moments.     

Infrared and raman spectroscopy of stressed polyethylene

Polyethylene films were stressed in uniaxial tension at room temperature while the infrared (FTIR) or Raman spectra were simultaneously measured. The purpose of these experiments was to gain an understanding of the molecular origins of the stress-induced vibrational frequency shifts Δν and determine the mechanisms of molecular deformation and fracture of PE molecules with stress σ. The PE samples consisted of ultradrawn, high-density, ultrahigh-molecular-weight, solid-state-extruded films and the stress was applied parallel to the nearly perfectly oriented orthorhombic crystal c-axis direction. The experimental frequency shifting coefficients α = (?ν/?σ)_σ→0 were compared with calculated α values determined from a vibrational analysis of an isolated PE chain using conformational energy minimization methods in which both harmonic and anharmonic (Morse) potential energy functions were used for the C? C stretching modes in the valence force field. The following α values were obtained and are compared with theory (anharmonic case in parentheses, in cm^?1/GPa): C? C symmetric stretch, α(1127) = ?5.9 (?5.3); CC asymmetric stretch, α(1059) = ?11.2 to ?5.7 (?5.8); CH₂ rock, α(730/720) = ?2.0 to ?3.0 (?2.2); CH₂ scissors, α(1472/1462) = ?1.0 to ?1.2 (?1.1); CH₂ twist, α(1295) ? 0(0.8); CH₂ wag, α(1370) undetermined owing to weak bands (?4.6); CH₂ stretch α(3000) ≈ 0. The largest negative frequency shifts were observed for the C? C stretching modes, in agreement with the calculations using the Morse potential. The harmonic potential for C? C stretching resulted in small positive α values for both the CC stretching and CH₂ wagging modes, while the other modes were unaffected by this choice of potential. The relative contribution of C? C bond stretching and C?C valence angle bending to the c-axis strain was about 1:1, in agreement with experiment. The Young's tensile modulus of a PE chain was calculated as E_c = 267 GPa.     

The high pressure nitric oxide mass spectra of aldehydes

The high pressure (0.5 Torr) nitric oxide mass spectra of some aldehydes, obtained using a 10% mixture of NO in N₂, are reported. The 10% NO/N₂ spectra of the monodeuterated analogs of some of them are compared to the electron-impact and methane chemical ionization spectra, especially with reference to the process of hydride abstraction by nitrosonium ions.     

Infrared spectra and rotational isomerism of epifluorohydrin and other propene oxide derivatives

The infrared spectrum for the vapour, liquid and solid states of epifluorohydrin has been studied, and evidence has been obtained for the presence of rotational isomers. The dominant conformer in all phases corresponds to a gauche structure, which was the only form identified in the vapour by microwave spectroscopy [1]. Similar evidence for conformational equilibria has been found for the chloro, bromo and iodo derivatives, and the enthalpy differences between the rotational isomers of these compounds were measured respectively as 4580 ± 970, 3950 ± 400, and 2350 ± 170 J mol^?1 respectively. At low temperatures, epiiodohydrin was found to crystallize in one of two possible crystalline phases. These two phases correspond to the two rotational isomeric conformations of the molecule.