IR spectroscopic studies of CO interaction with surface zirconium hydrides

IR spectroscopic studies of CO interaction with surface zirconium hydrides have revealed that it proceeds through a step of CO adsorption on these hydrides at 163–273 K with the subsequent insertion of CO across the Zr-H bonds at T>293 K and the formation of surface formyl compounds.

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CO . , CO 163–273 CO Zr-H 293 .

     

IR spectroscopic study of the reaction of polyalkylhydrosiloxanes with a silica surface

Using IR spectroscopy, we have studied the reaction of polyalkylhydrosiloxanes with a silica surface and the change in the chemical nature and structure of the modified layer upon its thermal oxidation. Upon modification of aerosil A-175 by polymethyl- and polyethylhydrosiloxane, the modifying agent molecules reacts with the surface OH groups. Some of the surface hydroxyl groups are not involved in chemical reaction with the modifying agent, but judging from the position of the corresponding OH-stretch band (3400 cm^–1) they experience the perturbing effect of the polyorganosiloxane film. Thermal oxidation leads to an increase in the number of the lateral bonds in the polyorganosiloxane-modified film; the maximum degree of crosslinking is observed in the case of the aerosil treated with polymethylhydrosiloxane.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 753–755, November–December, 1989.     

IR spectroscopic study of the interaction between trimethylgallium and arsine in the liquid phase

The formation of a donor-acceptor complex Me₃Ga · AsH₃ in a solution in liquid krypton at 130 K and in a binary liquid solution of those substances at 263 K was established by IR spectroscopy. In the latter case, Me₃Ga and AsH₃ react at an appreciable rate to form an amorphous product of composition Me_3-x ,GaAsH_3-x .Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2259–2262, September, 1996.     

It spectroscopic study of the interaction of chlorosilanes with the surface of aerosil

The surface-chemical reactions of the chlorosilanes

$$\left( {\begin{array}{*{20}c} {} & {} & {} & {{\text{CH}}_{\text{3}} } & {} & {} & {{\text{CH}}_{\text{3}} } & {} \\ {} & {} & {} & {} & {} & {} & {} & {} \\ {{\text{CL}}_{\text{3}} {\text{SiH,}}} & {{\text{CL}}_{\text{3}} {\text{Si}}} & {} & {} & {,{\text{ ClSi}}} & {} & {} & {\text{H}} \\ {} & {} & {} & {} & {} & {} & {} & {} \\ {} & {} & {} & {\text{H}} & {} & {} & {{\text{CH}}_{\text{3}} } & {} \\ {} & {} & {} & {} & {} & {} & {} & {} \\ \end{array} } \right)$$     

Ellipsometric study of the interaction of a germanium monocrystal with bromine

Using an ellipsometric technique, the dynamics of formation of adsorption layers in the process of interaction of bromine with a germanium monocrystal surface has been studied. It is shown that the reaction begins only when the second layer of bromine molecules is formed on the germanium surface. The ellipsometric data are in agreement with the results obtained by kinetic experiments.

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Эллипсометрическим методом исследована динамика адсорбционных заполнений во время химической реакции германия с бромом. Сделан вывод о том, что химическая реакция германия с бромом становится возможной только при адсорбции второго слоя молекул брома. Получено хорошее соответствие между результатами кинетических и эллипсометрических экспериментов.

     

Direct IR spectroscopic study of the cyclopentadienyl radical

The products of vacuum pyrolysis of bis(cyclopentadienyl)nickel have been studied by matrix isolation infrared spetroscopy. Three IR bands at 3079, 1383 and 661 cm^–1 corresponding to the cyclopentadienyl radical have been observed. A comparison of the IR spectrum of the radical C₅H₅ with those of the ligand -C₅H₅ and free anion^–C₅H₅ has been performed.These results were presented for the first time in O. M. Nefedov's plenary lecture at X IUPAC Conference on Physical Organic Chemistry (Haifa, Israel, August 1990) (see ref. 1 and literature cited therein).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1497–1499, August, 1993.     

Vibrational spectroscopic studies of the interaction of water with serine

The vibrational dynamics of water around serine was investigated by using Raman spectroscopy and inelastic incoherent neutron scattering. Experiments with serine in deuterium oxide were performed to assist the assignment. The study shows that for the serine, the exchange of protons-deuterons on the active -NH3+ and -OH groups were relatively easy, whereas there were hardly any exchanged on the -CH or -CH2- groups. The main features of the spectra for hydrated samples (versus the dry samples) were altered considerably; new sharp peaks in the measured spectra appeared, indicating that the hydrogen bonding between water and serine had disturbed the structure of the serine molecule.     

Generation and IR spectroscopic study of benzyl radical

The benzyl radical C₆H₅CH₂ has been obtained by gas phase pyrolysis of two different precursors, benzyl bromide and dibenzyl, and studied in an argon matrix at 12 K by IR spectroscopy. Similarly, the deuterosubstituted benzyl radicals, C₆H₅CD₂ and C₆D₅CH₂, have been investigated. The assignment of the IR bands of the benzyl radical and its deuteroanalogs to fundamental modes and a calculation of the valence force field have been performed. The obtained data give evidence of sp² hybridization of the methylene carbon atom and delocalization of the electron density between the ring and the CH₂ group, and are in good agreement with the planar structure of the radical.These results were presented for the first time in O. M. Nefedov's plenary lecture at X IUPAC Conference on Physical Organic Chemistry (Haifa, Israel, August 1990).Deceased July, 1986.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1499–1502, August, 1993.     

IR spectroscopic study of the complex formation between ammonia and water molecules in a KBr matrix

The formation of complexes of ammonia and water molecules in a potassium bromide matrix is studied by means of IR spectroscopy. Ammonia and water complexes of variable composition are stabilized in a solid matrix using different approaches to saturating KBr powder with the initial components. Proton transfer can occur, leading to the formation of ammonium salts.     

IR spectroscopic and calorimetric study of water and formic acid adsorption on a vanadium-titanium catalyst

Kinetics and Catalysis - Formaldehyde is oxidized to formic acid at a high selectivity over vanadium -titanium catalysts. IR spectroscopic and calorimetric techniques were used for studying the...     

IR spectroscopic study of filled polymeric films

Distribution of scattering centers (filler particles and pores) in films of an ultra-high-molecular-weight polyethylene xerogel was studied by IR spectroscopy and optical microscopy.     

An IR spectroscopic study of amorphous silicas

The IR absorption spectra of various amorphous silicas were studied. Depending on the conditions of the preparation of amorphous SiO₂, Si-O bonds with various strengths were formed in siloxane groups.     

A study of the interaction of dimethylcadmium and diethylcadmium with the Aerosil surface by IR spectroscopy and mass spectrometry

Dimethyl- and diethylcadmium interact with both free hydroxyl and siloxane groups of the Aerosil surface to form ≡Si-O-Cd-C≡ and ≡Si-H fragments. At 200 °C these structures undergo β-elimination to form surface ≡Si-O-Cd-H groups. It has been established that on heating to 600 °C, these groups decompose to afford metallic cadmium with the regeneration of the ≡Si-OH surface groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1717–1720, October, 1993.     

An IR spectroscopic study of acid centers on the surface of Al,Zr silica gels

Acid centers of Al, Zr silica gels with approximately equal aluminum ion contents (∼2.4% Al₂O₃) and various concentrations of Zr ions were studied by IR spectroscopy using the deuteroacetonitrile molecule as a probe. The surface of such samples was found to contain Lewis acid centers of two types, coordination unsaturated (I) silicon and (II) zirconium ions. An increase in the content of zirconium ions was accompanied by a decrease in the intensity of the 2328 cm⁻¹ band in the IR spectra. This band was characteristic of interaction of CD₃CN with Lewis acid centers of type I. The suggestion was made that this was caused by a decrease in the accessibility of coordination unsaturated silicon ions to CD₃CN molecules.     

Non-monotonic behaviour with concentration of the surface tension of certain binary liquid alloys

The surface tension σ(c) of most liquid binary alloys usually varies with concentration c in a monotonic way between the values σ₁ and σ₂ of the two pure metals, and this behaviour is well explained by current models. Some alloys show deviations from this ideal behaviour. One of those is Fe–B. The surface tension of this liquid alloy shows a minimum at 17 atomic % B, which corresponds well with the composition of the eutectic point in the phase diagram, followed by a maximum at a concentration of 24 atomic % B or higher. The usual models for the surface tension of liquid binary alloys do not explain those exceptional features, and we propose that a model involving the concentration fluctuations in the liquid alloy has the proper ingredients to account for the features in Fe–B and similar alloys.