Das Ultrarotspektrum von isotaktischem Polypropylen zwischen 1500 cm−1 und 330 cm−1

Zusammenfassung Die Frequenzen der Skelettschwingungen von isotaktischem Polypropylen werden mit Hilfe des Valenzkraft-Modells berechnet und mit den im UR-Spektrum gemessenen Frequenzen verglichen. Die übereinstimmung ist so gut, da? eine Zuordnung der Banden zu den Molekelschwingungen gegeben werden kann. Dagegen k?nnen die Intensit?tsverh?ltnisse nicht gekl?rt werden. Herrn Professor Dr.Hellwege danke ich für Anregungen und Diskussionen zu dieser Arbeit. Ferner danke ich den Firmen Kalle, Wiesbaden, und Farbwerke Hoechst für die zur Verfügung gestellten Polypropylenproben, der Deutschen Forschungsgemeinschaft für die Bereitstellung des Rechenautomaten und HerrnG. Günther für die Hilfe beim Programmieren.     

Infra-red spectra of monosubstituted benzenes in the 667-222 cm−1 region

The infra-red spectra in the 667-222 cm⁻¹ region of 29 monosubstituted benzenes as Nujol mulls and as carbon tetrachloride solutions (where possible) have been recorded. The vibrations of the molecule C₆H₅X which give rise to absorptions within this region have been discussed and it is shown that assignment of the principal bands is possible not only where X is a simple group but also for those cages in which X is a substituent of some complexity.     

Origin of the doublet at 1360 and 1340 cm−1 in the Raman spectra of tryptophan and related compounds

Raman spectra of indole, skatole, tryptophan and its derivatives including C₄-monodeuterated tryptophan were studied with special attention to the origin of the band around 1350 cm⁻¹. The band is observed as a doublet or triplet depending on the compound and solvent, which was ascribed to Fermi resonance between one fundamental and one or two combination bands of the out-of-plane bending vibrations. Removal of the interaction is seen for C₄D-tryptophan and some solutions of skatole. The assignments of the component vibrations were made based on the shifts in frequencies upon C₄-deuteration. In tryptophan derivatives the doublet (or triplet) peaks exhibit steep changes in relative intensity at the pK_a points of the dissociable groups, which is ascribed as arising from slight frequency shifts of a pK_a-sensitive component vibration. Relations between the relative intensity and environment of indole were obtained and their possible applicability to the analyses of Raman spectra of proteins is suggested.     

ATR-FT-IR spectral collection of conservation materials in the extended region of 4000-80 cm–1

In this paper, a spectral collection of over 150 ATR-FT-IR spectra of materials related to cultural heritage and conservation science has been presented that have been measured in the extended region of 4000-80 cm^–1 (mid-IR and far-IR region). The applicability of the spectra and, in particular, the extended spectral range, for investigation of art-related materials is demonstrated on a case study. This collection of ATRFT-IR reference spectra is freely available online (http://tera.chem.ut.ee/IR_spectra/) and is meant to be a useful tool for researchers in the field of conservation and materials science.     

A strong band at 1200 cm−1, characteristic of the −CH2−COOH group

Infra-red absorption spectra were observed for four isotopic species of succinic acid: HOOCCH₂CH₂COOH, DOOCCH₂CH₂COOD, HOOCCD₂CD₂COOH and DOOCCD₂CD₂COOD. Based on the results obtained, complete assignments were made for all the observed bands. Evidence is given that a strong band at 1205 cm⁻¹ of HOOCCH₂CH₂COOH is assignable to a vibration to which the greatest contribution is made by the CH2 wagging motion and much smaller contributions are made by the C−O stretching, C−C stretching, and OH in-plane deformation motions.     

Ozonization of sodium hydroxide in the temperature range from −100 tO +50°

Summary The process of ozonization of sodium hydroxide was studied in the temperature interval from –100 to +50°. The time and temperature dependences of the yield of sodium ozonide were obtained.     

Isotopic sohd solution frequencies and assignments in the 800 cm−1 region in dimethylsilanes

Infra-red spectra of solid solutions of isotopic samples of dimethylsilanes have been measured and some frequency assignments have been made.     

Crystal chemical and dielectric investigation of the system LiZnV1−xPxO4

An X-ray crystallographic study has allowed us to identify a solid solution of the type LiZnV_1−xP_xO₄ (0≤ x ≤0.6) inside the binary system LiZnVO₄-LiZnPO₄. The structure is isotypic with the phenacite like LiZnVO₄. X-ray diffraction patterns are indexed according to the lattice parameters of the trigonal system and the space group R3. The mother structure can be regarded as made of a three-dimensional network of LiO₄, ZnO₄ and VO₄ tetrahedra all having one apex oriented along [001]. The peaks, observed on the curves of the thermal variation of the dielectric constants, have allowed us to recognize a phase transition whose temperature varies continuously along the solid solution.     

Infrared spectra of triacetylene in the 4000-220 cm−1 region: Absolute band intensity and implications for the atmosphere of Titan

The gas phase infrared spectra of triacetylene were studied at room temperature in the 4000-220 cm⁻¹ wavenumber region. The absolute intensity of all the bands of noticeable strength were experimentally determined and the associated uncertainties were systematically estimated. The data obtained were then used for studying the detectability of C₆H₂ in Titan's atmosphere by means of infrared spectroscopy. The upper limit of mean stratospheric abundance derived from the already available Titan IR spectra (a fraction of ppb) is in agreement with the photochemical model estimates.     

Spectroscopy of H 3 + with energies above the barrier to linearity: rovibrational transitions in the range of 10,000–14,000 cm−1

Based on a recently extended potential energy surface for H ₃ ⁺ with a highly reliable form of the topology of the surface far beyond the barrier to linearity, rovibrational frequencies in the range of 10,000–14,000 cm^?1 have been derived and are compared with new experiments. The computed transition frequencies reproduce experimental transitions mostly within a few tenths of a wavenumber, if non-adiabatic effects are crudely simulated using different reduced masses for vibrational and rotational motions. Deviations can only be compensated if non-adiabatic effects are treated more rigorously.     

Infrared spectra of chelate compounds—IV: A study of the uranyl chelates of 8-hydroxyquinoline in the region 5000-250 cm−1

Previous investigations have shown that two different uranium chelates of 8-hydroxyquinoline can be precipitated from homogeneous solution. Dark red UO₂(C₉H₆NO)₂·C₉H₆NOH is obtained at pH 5.0 and orange [UO₂(C₉H₆NO)₂·C₉H₆NOH at pH 6.8; the normal chelate UO₂(C₉H₆NO)₂ is green. The infrared spectra of the solvated compounds have been examined in the range 5000-250 cm⁻¹ and that of the normal chelate in the range 5000-650 cm⁻¹. From this it is concluded that the solvated chelates have very similar structures.     

The infrared spectra of some aliphatic monocarboxylic acids in the 700-350 cm−1 region

The infrared spectra of 28 aliphatic monocarboxylic acids of varying structure are recorded in the 700-350 cm₋₁ region. It is shown that the structural configuration adjacent to the carbonyl group affects the spectra in a specific manner. It is therefore possible to differentiate α-alkyl branched acids from straight-chain acids. Striking differences in the spectra of liquid and solid forms of the straight-chain acids were observed. The spectra of the solids below about 510 cm⁻¹ are quite characteristic of the individual acids and may be used for differentiation of these compounds.     

Comparative investigation of LiNbO3 crystals Raman spectra in the temperature range 100–400 K

We have investigated Raman spectra of congruent and stoichiometric LiNbO₃ crystals in the temperature range 100–450 K. Slope gradient is greater for the temperature dependence of band width associated with Nb⁵⁺ ions vibrations than that associated with Li⁺ ions vibrations in a lithium niobate crystal structure. This fact indicates that the anharmonicity of Nb⁵⁺ ions vibrations along the polar axis is greater compared to Li⁺ ions vibrations. It is likely that O^2– ions contribute to this anharmonicity. The O^2– ions vibrations are characterized by an anharmonic potential in the LiNbO₃ crystal structure. The O^2– ions vibrations according to ab initio calculations strongly interact with vibrations of Nb⁵⁺ ions. We have found that the temperature dependence of the fundamental bands intensity is nonmonotonic and the “extra bands” intensity is strictly linear.     

The infrared spectra of tin(IV) tetrahalides and dialkyltin dihalides in the 500-50 cm−1 region

The infrared spectra of tin(IV) tetrahalides SnX₄ (XCl, Br and I) have been recorded, in cyclohexane solution, using a Michelson interferometer and the ν₃ and ν₄ fundamentals assigned.     

Effect of pH and α-, β- and γ-cyclodextrin on the spectral properties of etoricoxib: spectroscopic and molecular dynamics study

The spectral properties of etoricoxib (ETR) at pH 2.0, 6.0 and 10.0 in the presence of cyclodextrins (CDs) were investigated. The absorption spectrum of ETR in acidic medium exhibited two bands centered at 236 and 273 nm, while in basic medium it exhibited two bands centered at 236 and 285 nm. No change in the spectrum was observed in the presence of CDs. The fluorescence emission spectra of ETR in acidic and basic media exhibited one band at 380 nm and another one at 484 nm. The emission band at 484 nm was enhanced when ETR was complexed with β-CD and γ-CD at pH 2.0, 6.0 and 10.0, while the band at 380 nm was enhanced selectively when ETR was complexed with α-CD at pH 2.0. Molecular dynamics simulations computations revealed that at pH 2.0, the sulfonyl moiety of H₂ETR²⁺ is preferentially included within the α-CD cavity, which is believed to cause the enhancement of the band at 380 nm. Moreover, at pH 6.0 and 10.0, the enhancement of the band at 484 nm was related to the inclusion of the chloropyridinyl and methylpyridinyl groups of the bipyridine moiety of HETR⁺ and ETR within β-CD and γ-CD cavities. Benesi–Hildebrand analysis showed that the ETR/β-CD complex adopts a 1:1 stoichiometry with association constant of K ₁₁?=?64.8 at pH 2.0, K ₁₁?=?105.4 at pH 6.0 and K ₁₁?=?520.5 at pH 10.0.     

Optical waveguide dosimetry for gamma-radiation in the dose range 10-1 − 104 Gy

Two types of liquid-core optical waveguide (OWG) dosimeters are commercially available for dosimetry in the irradiation of foods and other products. “Opti-chromic” type FWT-70-40M has a useful range of about 10-10⁴ Gy and type FWT-70–83M about 10²−10⁴ Gy. 5 Within the limits of random uncertainty of the reading of the absorbed dose (±5%, 1σ), the response to γ-radiation is independent of dose rate over the range 10^-1−10⁴ Gy/h, when measured at the peak of the spectrum [absorption band maximum (600 nm wavelength)]. The response curve is linear with dose up to ≈10³ Gy, but is non-linear at higher doses, where the readings are made away from the absorption peak (656nm). Both dosimeter types when measured at 600 nm are temperature dependent over the temperatures ranges of -40 to 60°C during irradiation. The dosimeters cannot be used when exposed to temperatures > 60°C because of bubble formation and loss of light propagation. At doses < 10³ Gy (at600 nm), the dosimeters are stable (in terms of dose readings) for several months following irradiation, but at doses ≈ 10⁴ kGy (at 656 nm), they show a gradual absorbance increase (error in dose interpretation), over post-irradiation storage periods longer than 1 month. A special, sensitive OWG dosimeter (50-cm coil), designed for doses down to 10^-1 Gy, shows a linear response up to at least 15 Gy, a temperature dependence of response only at temperatures below ≈ 20°C, and no dose-rate dependence.