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The mathematical model of distribution of the temperature fields during the process of saving drying of buckwheat grain with the superheated steam has been found. The given solution may be used to investigate the process of heat transfer in the objects with triangular symmetry.

The transformations of 1-substituted tetrahydro-β-carbolines by the action of activated alkynes were studied. The action of dimethyl acetylenedicarboxylate in methanol gives products of the opening of the tetrahydropyridine fragment, namely, 2-methoxyalkylindoles. The action of ethyl propiolate in ethanol and of tosylacetylene in methanol gives mixtures of azocino[5,4-b]indoles and 2-alkoxyindoles. The action of ethyl propiolate in acetonitrile gives azocinoindoles.

The processes of stepwise ionization of the 2,4-dioxybenzaldehyde and 3,4-dimethoxypropiophenone vapors by radiation in the range of wavelengths down to 266 nm were studied using total-current spectroscopy, mass spectrometry, and photoelectron spectroscopy. The process of two-step ionization and the resulting generation of molecular ions are dominant if the laser-radiation intensity amounts to ≈106 W/cm2. These molecular ions have appreciable (up to 1.8 eV) energy of vibrational excitation. As the laser-radiation intensity increases, progressively more pronounced fragmentation occurs owing to dissociation of molecular (and, possibly, fragmentation) ions as a result of absorption of at least a single additional photon. The processes leading to fragmentation of ions are suggested. It is found that the dissociation-ionization mechanism is important for the dimethoxypropiophenone. Dissociation with a breakage of the α bond in the carbonyl group with subsequent two-photon ionization of the fragments occurs when the S 2(1 A′) state of the ππ* type is excited.

Processes of stepwise ionization of 1,2-dimethoxybenzene vapor by radiation in the range 295-275 nm were studied by the techniques of total current spectroscopy, mass spectrometry, electronic absorption spectroscopy, and threshold electron spectroscopy. A two-step ionization process via the first electronically excited state of the molecule yielding the molecular ion was found to prevail at an average laser radiation intensity less than 106 W/cm2. Molecular ions possess a considerable (up to 1 eV) vibrational excitation energy. As the radiation intensity increases, the progressively stronger and deeper degradation takes place via dissociation of molecular and, probably, fragment ions due to absorption of at least one additional photon.

Processes of stepwise ionization of hydroquinone vapor by radiation in the range 315–275 nm were studied using photoionization spectroscopy techniques. The two-step ionization process yielding molecular ions was found to prevail at a laser power density up to ∼107 W/cm2. As the radiation intensity increases, the progressively stronger and deeper degradation takes place via dissociation of the molecular and, probably, fragment ions due to absorption of at least one additional photon. The slow process of the formation of C5H6O0 ions at an effective rate constant of the order of 106 s−1 was observed.

The transformations of 1-substituted tetrahydro-β-carbolines by the action of activated alkynes were studied. The action of dimethyl acetylenedicarboxylate in methanol gives products of the opening of the tetrahydropyridine fragment, namely, 2-methoxyalkylindoles. The action of ethyl propiolate in ethanol and of tosylacetylene in methanol gives mixtures of azocino[5,4-b]indoles and 2-alkoxyindoles. The action of ethyl propiolate in acetonitrile gives azocinoindoles.

A new group of electrons in the naphthalene ZEKE PFI spectrum has been observed in the energy range 70000 - 72000 cm-1 by the one-color two-step laser excitation technique. It can be assigned to the field ionization of the high n Rydberg states converging to the first electron-excited ionic state of naphthalene. The lifetimes of the superexcited Rydberg states with the energy excess (above the first ionization energy) up to 1 eV are about 1 microsecond. The improved value of the second adiabatic ionization potential is 71823 plus or minus 30 cm-1 (8.904 plus or minus 0.004 eV).© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The He-1 photoelectron spectra of a number of (alkylthiomethyl)trimethoxysilanes with the formula RSCH/sub 2/Si(OMe)/sub 3/ (R = Me, Et, Pr, Bu, Me/sub 2/CHCH/sub 2/, Me/sub 3/C) have been studied. The highest two MOs in the molecules of these compounds are close in energy, but differ strongly in nature. The first of them consists mainly of a sulfur p AO and is perpendicular to the plane of the CSC group, and the other one includes s and p AOs of the S atom with a similar contribution from the S/sup +/C and Si-C bonds and is destabilized by the interaction of the n electrons of the S and O atoms through the intermediate bonds. In the molecule of (tert-butylthiomethyl)trimethyoxysilane the fraction of the cis conformations is apparently reduced owing to the steric interaction. The values of the Kabachnik and Taft induction constants of the CH/sub 2/Si(OMe)/sub 3/ group have been determined from the spectroscopic characteristic (sigma/sup i/ = -1.30 and sigma* = -0.25).

The changes in the chemical shifts of organic molecules during complex formation are well known in organometallic chemistry [24]. Thus, coordinated dienes lose the olefinic characteristics; they are not hydrogenated, do not enter into the Diels-Alder reaction, and react with electrophilic reagents. At the present time the search for a link between the structure of organometallic complexes in terms of rigorous quantum-chemical calculations is beginning. The construction of experimentally substantiated models which make it possible to explain qualitatively the marked changes in the characteristics of organic compounds in the presence of the atoms of transition metals is therefore essential for a deeper understanding of the orbital mechanisms lying at the basis of catalysis.