Gas-phase reactions of O(3P) atoms with methanethiol, ethanethiol, methyl sulfide, and dimethyl disulfide. 2. Reaction products and mechanisms

1981 ◽  
Vol 103 (12) ◽  
pp. 3530-3539 ◽  
Author(s):  
R. J. Cvetanovic ◽  
D. L. Singleton ◽  
R. S. Irwin
Keyword(s):  
Gas Phase ◽  
Dimethyl Disulfide ◽  
Reaction Products ◽  
Gas Phase Reactions ◽  
Methyl Sulfide

A Study on Film Precursors in SiH4 Thermal CVD by use of Trench Coverage Measurements

1989 ◽  
Vol 146 ◽  
Author(s):  
Akimasa Yuuki ◽  
Takaaki Kawahara ◽  
Yasuji Matsui ◽  
Kunihide Tachibana
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Reaction Products ◽  
Gas Phase Reactions ◽  
Cross Sectional ◽  
Thermal Cvd ◽  
Silane Molecule ◽  
Cross Sectional Profile ◽  
Sticking Probabilities ◽  
Sectional Profile

ABSTRACTThe precursors of Si film in SiH4 low pressure thermal CVD are studied by use of the trench coverage analysis. The cross sectional profile of the film deposited in a trench is simulated by a direct Monte-Carlo method using the composition of the precursors and their sticking probabilities as adjustable parameters. A comparison with the experimental results[1] shows that the trench coverage profiles are well reproduced by the model where two kinds of precursors deposit independently with respective sticking probabilities of almost zero and unity. The former is silane molecule, and the latter is radicals produced by gas phase reactions. The deposition rate due to radicals can be estimated from the comparison. Considering the sticking probability and the SiH4 pyrolysis reactions, it is concluded that H3SiSiH is one of ate dominant film precursors in gas phase reaction products.

Thiirene formation in the reactions of sulfur atoms with alkynes

1983 ◽  
Vol 61 (10) ◽  
pp. 2268-2281 ◽  
Author(s):  
Bela Verkoczy ◽  
Alden G. Sherwood ◽  
Imre Safarik ◽  
Otto P. Strausz
Keyword(s):  
Gas Phase ◽  
New Products ◽  
Reaction Products ◽  
Gas Phase Reactions ◽  
Bimolecular Reactions ◽  
Primary Products ◽  
End Products ◽  
Secondary Reactions

The gas phase reactions of S(1D2) and S(3PJ) atoms with alkynes have been studied by photolyzing COS in the presence of CH≡CH, CF3C≡CH, and CF3C≡CCF3. In the reactions with CH≡CH, CS2, benzene, and thiophene were formed; with CF3C≡CH, eight products were found with disubstituted thiophenes and trisubstituted benzenes as the major products. In the case of CF3C≡CCF3, only perfluorotetramethylthiophene was detected at low conversion but at long photolysis several new products were observed. Many of the reaction products characterized here have not been reported before.The formation and distribution of the reaction products could be rationalized by an overall mechanism in which the formation of the highly reactive primary adducts, thiirene and thioformylmethylene, is followed by bimolecular reactions yielding the principal end products. The formation of minor products could be explained by secondary photoisomerizations, secondary photolysis, and by secondary decompositions and the secondary reactions of sulfur atoms with primary products.

Gas-phase heteroaromatic substitution. 11. Electron transfer mechanism in the gas-phase acylation of simple five-membered heteroarenes

1991 ◽  
Vol 69 (4) ◽  
pp. 740-748 ◽  
Author(s):  
Antonello Filippi ◽  
Giorgio Occhiucci ◽  
Cinzia Sparapani ◽  
Maurizio Speranza
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Reaction Products ◽  
Ion Chemistry ◽  
Gas Phase Reactions ◽  
Β Decay ◽  
Electron Transfer Mechanism ◽  
Gas Phase Ion Chemistry ◽  
Mass Spectrometric Evidence ◽  
Gas Phase Ion

The results of a study of the gas-phase reactions of unsaturated carbocations, such as the CH3CO+ ion from γ-radiolysis of CH3F/CO mixtures, and the C6H4TCO+ ion from the β-decay of 1,4-ditritiobenzene in the presence of CO, with pyrrole, N-methylpyrrole, furan, and thiophene, are reported. In all systems investigated, acylated heteroarenes represent the predominant reaction products, accompanied by the methylated derivatives in the CH3F/CO radiolytic mixtures, and by the phenylated ones in the 1,4-ditritiobenzene/CO decay samples. All substrates investigated are found to undergo predominant α substitution by both acetyl (88.6–98.4% (pyrrole); 90.8–98.7% (N-methylpyrrole); 97.2–98.9% (furan); 94.9–98.6% (thiophene)) and benzoyl cations (92.6–96.5% (pyrrole)) under all conditions. The predominant formation of the α-acylated pyrroles from both reactants (>88%), whose relative yields appear unaffected within the temperature interval from 303 to 383 K, indicates, in agreement with ancillary FT-ICR mass spectrometric evidence, that gas-phase acylation reactions toward simple five-membered heteroarenes proceed via a two-step substitution mechanism, involving a quasi-resonant single-electron transfer (SET) step followed by recombination of the ensuing radical – radical ion pair. By virtue of this entropy-favored mechanism, gaseous electrophiles with relatively high SCF STO-3G calculated LUMO energies such as CH3CO+ and C6H4TCO+ are effectively oriented toward the "soft" Cα sites of the selected heteroarenes, at variance with Klopman's Charge and Frontier Orbital Control predictions. The behavior of gaseous acylating reactants toward simple heteroarenes is discussed and compared with that of other gaseous electrophiles, whose reactivity appears instead in qualitative agreement with Klopman's model. Key words: gas-phase ion chemistry, electrophilic heteroaromatic substitution, nuclear decay and radiolysis, acylium ions, electron transfer.

scholarly journals Gas-Phase Reactions in the ISM: Rate Coefficients, Temperature Dependences, and Reaction Products

2011 ◽  
Vol 7 (S280) ◽  
pp. 361-371 ◽  
Author(s):  
Ian W. M. Smith
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
Rate Coefficients ◽  
Reaction Products ◽  
Empirical Methods ◽  
Gas Phase Reactions ◽  
Rich Variety ◽  
Temperature Dependences ◽  
The Rich ◽  
Semi Empirical

AbstractInformation about the rate coefficients and products of processes that occur in the interstellar medium are required as input to computer models that seek to reproduce the abundances of the rich variety of molecules that have been observed in different regions of the interstellar medium. In this brief review, I seek to identify the different kinds of gas-phase processes for which information is required and to consider the experimental, theoretical, and semi-empirical methods which are employed to measure or predict rate coefficients, k(T), and how they depend on temperature (T) – and also how the products of reactions can, in favourable cases, be observed.

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