An infrared spectroscopic study of the adsorption of NO, CO and NO + CO on α-Fe2O3 was carried out in order to identify chemisorbed species and discuss adsorption sites. Stable nitrate species are formed on the surface at beam temperature (b.t.) when NO is adsorbed. Depending on the pressure, NO adsorbs at b.t. also to form Fe3+ (NO) species. Only a weakly adsorbed species, coordinated with a cationic sites to form different types of carbonates is observed at high temperature adsorption (473 - 523 K). In the presence of NO + CO mixture, stable nitrate ions are formed when temperature is increased from b.t. to 423 K. At higher temperature (473 - 523), NO and CO mainly chemisorb as nitrates and carbonates in to an adsorption of NO on partially reduced cationic sites : Fe(3-δ)+(NO); Fe2+(NO).
H. Batis, N. Harrouch, A. Ghorbel
Pages 51-58
Tin oxide and Zinc-Cadmium sulfide films were prepared by airless Spray. With this technique the growth rate is higher than by pneumatical Spray. The efficiencies of the Solar cells CdS/Cu2S and Cd0.9Zn0.1S/Cu2S are respectively about 2.6 % and 3.2 %.
M. Dachraoui, S. Belgacem, R. Bennaceur, H. Latrous
Pages 59-61
In recent years, many types of systems which enable the conversion of solar energy into electrical or chemical energy have been proposed. This work is a review of the electrochemical cells proposed in literature. For comparison, some results of photovoltaic cells are cited.
M. Dhahbi (ex. Hamdi)
Pages 63-74
The synthesis of pyrazolenines derived from dissymetric monoactivated acetylenics of which the second substituant is n-alkyl has been realized stoechiometrically. This result was obtained by addition 1,3-dipolar of diazo-2 propane to the starting acetylenics. In the same way, all the photolysies of the mono-activated pyrazolenines have enabled us to get exclusively the expected mono-activated gemdimethylcyclopropene.
A. Khemiss, M. Franck-Neumann
Pages 3-12
The Z/E olefinic bond ration of enol ethers obtained by Oxy-Cope rearrangement of hetero-substituted 1,5-hexadienes reveals that the reaction is not governed by the free energy change for the conversion of a substituent from the equatorial to the axial position in the chair transition state but rather by the relative thermodynamic stability of the isomers Z and E.
R. Abdelhedi, M.L. Bouguerra, J. C. Pommelet, J. Chuche
Pages 13-17
Addition compounds of the type 1 : 1, 1 : 2 and 1 : 4 are obtained as a result of tin (IV) chloride action with cyclohexanol derivates in petrolium ether. Infrared study and elementary analysis confirm these results.
S. Jarraya, C. Devin
Pages 19-23
The oxidation of propylene over the Tin-Antimony oxide catalysts has been proved to be sensitive to the composition of the reactional mixture. This composition affects the stability of the catalyser during the reaction and the fonctionning of its busy centres.
B. Bejar, N. Zenaidi, A. Ghorbel
Pages 25-32
The low frequency Raman Spectra (0 - 350 cm-1) of [(CH3)2 NH2]2 Sn Cl6 (2MHS) and [(CH3)3 NH]2 Sn Cl6 (3MHS) were recorded on single crystals at room temperature. The Spectra have been assigned on the basis of group theory analysis of vibrations and in view of the previously reported structural data of these two hexachlorostannate compouds. Their corresponding structures are derived from the Fm3m antifluorite structure.
M.H. Ben Gozlen, Y. Mlik, A. Daoud
Pages 33-37