Calculation of the Spectrum of Chemical Relaxation Times for a General Reaction Mechanism

1963 ◽  
Vol 67 (9-10) ◽  
pp. 898-908 ◽  
Author(s):  
Gilbert W. Castellan
Keyword(s):  
Reaction Mechanism ◽  
Relaxation Times ◽  
General Reaction ◽  
Chemical Relaxation

Non Radiative Electronic Transitions in Ionic Crystals I* Crystal model and calculation of states

1969 ◽  
Vol 24 (4) ◽  
pp. 516-530
Author(s):  
Alf Löffler
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Microscopic Theory ◽  
Anion Vacancy ◽  
Electronic Transitions ◽  
Ionic Crystals ◽  
Matrix Elements ◽  
General Reaction ◽  
Crystal Model ◽  
Crystal Volume

Abstract The theory of non radiative electronic transitions is represented in two papers. In the first of these we calculate wavefunctions, energies, matrix-elements etc. In the second we discuss the general reaction mechanism and apply the theory to two examples. The wavefunction of a crystal volume containing one defect is calculated on the base of a microscopic theory. For our numerical discussion we used as an example an anion vacancy in MgO, LiF, NaCI, NaBr, KC1, KBr, KJ. The results are collected in Table 1 and 2. As far as experimental data have been available they agree completely with our results.

scholarly journals A general reaction mechanism for carbapenem hydrolysis by mononuclear and binuclear metallo-β-lactamases

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
María-Natalia Lisa ◽  
Antonela R. Palacios ◽  
Mahesh Aitha ◽  
Mariano M. González ◽  
Diego M. Moreno ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
General Reaction

Oberflächenverbindungen von Übergangsmetallen, XVI Chemilumineszenz bei der Oxydation koordinativ ungesättigter Oberflächenverbindungen / Surface Compounds of Transition Metals, XVI Chemiluminescence Phenomena in the Oxydation of Coordinatively Unsaturated Surface Compounds

1976 ◽  
Vol 31 (6) ◽  
pp. 774-779 ◽  
Author(s):  
Peter Morys ◽  
Roger Gerritzen ◽  
Hans-Ludwig Krauss
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Transition Metals ◽  
Electronic Structures ◽  
Metal Ion ◽  
Peroxo Complex ◽  
General Reaction ◽  
Surface Compounds ◽  
Broad Emission

The reduced, coordinatively unsaturated surface compounds of chromium, vanadium and molybdenum, supported on silicagel, react with O2 under chemiluminescence; the extremely broad emission bands have their maxima at v = 15,0 kK (chromium), 18,6 kK (vanadium) and 20,6 kK (molybdenum).A general reaction mechanism is proposed based on the electronic structures of the starting, intermediate and final products. It allows an interpretation of the observed chemiluminescence phenomena in agreement with other experimental data; the desactivation of a CT excited peroxo complex of do metal ion is postulated as source of radiation.

Reactions at the Interface Between Al2O3–SiO2 Ceramics with Additives of Alkaline-earth Oxides and Liquid Al–Si Alloy

2002 ◽  
Vol 17 (3) ◽  
pp. 641-647 ◽  
Author(s):  
M. Oliveira ◽  
S. Agathopoulos ◽  
J. M. F. Ferreira
Keyword(s):  
Reaction Mechanism ◽  
Phase Formation ◽  
Alkaline Earth ◽  
Active Role ◽  
Interfacial Reactions ◽  
Metal Phase ◽  
General Reaction ◽  
Alkaline Earth Oxide ◽  
Reaction Zones

The interfacial reactions between aluminosilicate ceramics doped with MgO, CaO, or BaO and Al–7 wt% Si alloy were investigated at 1023, 1173, and 1323 K under vacuum for 4 h. Alkaline-earth oxide additives defined phase formation and microstructure of the sintered ceramics and subsequently controlled the ceramic/metal interfacial reactions, which were always intensive. In general, reaction zones consisted of Al2O3, infiltrated with Al. In the case of CaO- and BaO-doped ceramics, precipitates formed into the metal phase and concentrated the reduced Ca and Ba, respectively. A reaction mechanism is proposed, which anticipates an active role of SiO2.

scholarly journals THEORETICAL STUDY OF CHLORINATION REACTION OF NITROBENZENE FROM DFT CALCULATIONS

2015 ◽  
Vol 11 (9) ◽  
pp. 3784-3793 ◽  
Author(s):  
Ibrahim NDASSA MBOUOMBOUO ◽  
Gouet Bebga ◽  
Martin Signé ◽  
François Volatron ◽  
Bernard Silvi
Keyword(s):  
Reaction Mechanism ◽  
Surface Energy ◽  
Gas Phase ◽  
Density Functional ◽  
Potential Surface ◽  
Density Functional Theory Calculations ◽  
Aluminium Chloride ◽  
Stationary Points ◽  
Chlorination Reaction ◽  
General Reaction

The geometric parameters of stationary points on the potential surface energy of the chlorination reaction of nitrobenzene in the presence of Aluminium chloride as catalyst were investigated theoretically by hybrid DFT (Density Functional Theory) calculations in order to determine his general reaction mechanism in gas phase and in solution. The results obtained by DFT have been compared with CCSD(T) method which is the most powerful post-Hartree Fock method in terms of inclusion of dynamic correlation. Although the electrophilic substitution reaction is widely taught in most courses in organic chemistry, the mechanism has been very few studied theoretically. The results obtained in gas phase are consistent with the traditional description of these reactions: the orientation of this substitution in meta position depends on the stability of a reaction intermediate (Wheland said). Without taking in consideration the reactants and products, six stationary points are found on the potential surface energy of this reaction. The reaction has also been studied in the presence of solvent and we’ve noted that the influence of solvent decreases the electrostatic attraction on the Wheland complex, but the general reaction mechanism remains unchanged in solution.

Sydnone Photochemistry: Direct Observation of Earl's Bicyclic Lactone Valence Isomers (Oxadiazabicyclo[2.1.0]pentanones), Formation of Carbodiimides, Reaction Mechanism, and Photochromism

2014 ◽  
Vol 67 (3) ◽  
pp. 457 ◽  
Author(s):  
Rakesh N. Veedu ◽  
David Kvaskoff ◽  
Curt Wentrup
Keyword(s):  
Infrared Spectroscopy ◽  
Reaction Mechanism ◽  
Direct Observation ◽  
Matrix Isolation ◽  
General Reaction ◽  
The Matrix ◽  
Nitrile Imines ◽  
Bicyclic Lactones ◽  
Bicyclic Lactone

The matrix photolyses of 3-phenyl-, 3-pyridyl, and 3,4-diphenylsydnones 16, 19, and 22 were investigated by matrix-isolation infrared spectroscopy. The formation of the neutral, bicyclic lactone valence isomers postulated by Earl – the oxadiazabicyclo[2.1.0]pentanones exo-17 and exo-20 – was clearly observed in the first two cases and is also likely in the case of exo-23 (C=O absorptions in the IR at 1881, 1886, and 1874 cm–1, respectively). The efficient photodecomposition of sydnones to carbodiimides RN=C=NR′ (18, 21, and 24) and CO2 was established in all three cases. The formation of benzonitrile 27 and azacycloheptatetraene 29 in the matrix photolysis of diphenylsydnone 22 is indicative of diphenylnitrile imine PhCNNPh 26 as an intermediate (2340 cm–1). Neither bicyclic lactones nor carbodiimides have been observed previously in sydnone photochemistry. A general reaction mechanism for the formation of carbodiimides, nitrile imines, and photochromism is put forward.

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