Cobalt thin films are deposited by metal-organic (MO)CVD, under various experimental conditions, on Si and SiO 2 substrates. The precursors used are cobalt nitrosyl tricarbonyl, Co(CO) 3 NO, cobalt acetylacetonate, Co(acac) 2 , and cobalt carbonyl, Co 2 (CO) 8 . Emphasis is given to the delivery method of each precursor, especially to a new technique of aerosol delivery. The films are thoroughly examined in terms of microstructure and surface morphology in order to establish relevance to magnetic properties. It is found that Co films deposited from Co 2 (CO) 8 dissolved in dichloromethane are characterized by a high degree of planarity and purity, while exhibiting a non-hysteretic giant magnetoresistance (GMR) behavior in the presence of an externally applied magnetic field normal to their surface.

Biodegradation of phenol, a pollutant derived from many industrial processes, was achieved through acclimatized Pseudomonas putida cells. The strategy to overcome the inhibitory effect of phenol on microbial growth involved the addition of glucose, a conventional carbon source. A factorial experimental design was employed in order to optimize the initial phenol and glucose concentrations. The optimum conditions found were applied in 2-lt bioreactors. The development of acclimatized cells and the use of glucose as an added growth substrate resulted in a significant phenol degradation rate of 60.7 mg L(-1) h(-1) with a complete removal of 1200 mg L(-1) phenol.

8453that give rise to the model, are not predicted to be especially important in the overall energy transfer (in the same way that individual solvent molecule/particle collisions in macroscopic Brownian motion do not contribute much to the overall diffusive motion): indeed, in the most primitive version of the model, the average energy transfer is Seen to be completely independent of the highest-frequency modes of the substrate.1° ConclusionsTrajectory calculations and the BRW model agree with experiments on related systems: that there should be only a small isotope effect in the energy transfer between highly excited azulene and monatomic bath gases. This suggests that the low-frequency modes have an important role to play in determining the amount of energy transfer. In particular, the lack of any strong effect with helium suggests that classical calculations can provide an adequate representation, and the poor accord between experiment and trajectory results for light bath gas= is due to the poor description of the interaction potential. The results also predict that isotopic substitution should not have a strong effect on the fraction or the magnitude of supercollisions. Acknowledgment.An application of classical thermodynamics is made in the case of surface phase transitions occurring throughout a charged interphase. This kind of surface phase transitions characterizes the aggregation of micelle-forming surfactants within the interphase formed between electrolyte solutions and an ideally polarized electrode, at least at concentrations higher than the critical micelle concentration. On the basis of a multilayer model for the electrical double layer, the thermodynamic conditions for its stability and the reversibility of a pbseparation proc~ss which extends along the double layer are established. It is further shown that a rigorous but sufficient thermodynamic criterion for a surface micellization to take place across a charged interphase is the existence of two deformed peaks in the differential capacity versus applied potential curves on both sides of the adsorption maximum. The peaks may have comers and/or abrupt vertical segments and they may be split into two or more parts. Moreover, due to hysterisis phenomena their shape may depend on the potential scan rate and scan direction. Some expected deviations from the above criterion are also discussed.

The adhesion and mechanical stability of thin film coatings on substrates is increasingly becoming a key issue in device reliability as magnetic and storage technology driven products demand smaller, thinner and more complex functional coatings. In the present study, chemical vapor deposited Co and Co3O4thin films on SiO2and Si substrates are produced, respectively. Chemical vapor deposition is the most widely used deposition technique which produces thin films well adherent to the substrate. Co and Co3O4thin films can be used in innovative applications such as magnetic sensors, data storage devices and protective layers. The produced thin films are characterized using nanoindentation technique and their nanomechanical properties (hardness and elastic modulus) are obtained. Finally, an evaluation of the reliability of each thin film (wear analysis) is performed using the hardness to elastic modulus ratio in correlation to the ratio of irreversible work to total work for a complete loading-unloading procedure.

Magnetic iron oxide nanoparticles synthesized by coprecipitation and thermal decomposition yield largely monodisperse size distributions. The diameters of the coprecipitated particles measured by X-ray diffraction and transmission electron microscopy are between approximately 9 and 15 nm, whereas the diameters of thermally decomposed particles are in the range of 8 to 10 nm. Coprecipitated particles are indexed as magnetite-rich and thermally decomposed particles as maghemite-rich; however, both methods produce a mixture of magnetite and maghemite. Fourier transform IR spectra reveal that the nanoparticles are coated with at least two layers of oleic acid (OA) surfactant. The inner layer is postulated to be chemically adsorbed on the nanoparticle surface whereas the rest of the OA is physically adsorbed, as indicated by carboxyl O-H stretching modes above 3400 cm(-1). Differential thermal analysis (DTA) results indicate a double-stepped weight loss process, the lower-temperature step of which is assigned to condensation due to physically adsorbed or low-energy bonded OA moieties. Density functional calculations of Fe-O clusters, the inverse spinel cell, and isolated OA, as well as OA in bidentate linkage with ferrous and ferric atoms, suggest that the higher-temperature DTA stage could be further broken down into two regions: one in which condensation is due ferrous/ferrous- and/or ferrous/ferric-OA and the other due to condensation from ferrous/ferric- and ferric/ferric-OA complexes. The latter appear to form bonds with the OA carbonyl group of energy up to fivefold that of the bond formed by the ferrous/ferrous pairs. Molecular orbital populations indicate that such increased stability of the ferric/ferric pair is due to the contribution of the low-lying Fe(3+) t(2g) states into four bonding orbitals between -0.623 and -0.410 a.u.