Nanostructural characterization of amorphous diamondlike carbon films

Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetic and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of 3- and 4-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetic of PLD growth results in films becoming more ``diamondlike'', i.e. increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to material within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film

A study of laser-ion-deposited carbon films on tungsten by x-ray diffraction, field ion microscopy, and electron spectroscopy

Thin carbon films have been deposited on polycrystalline tungsten foil as well as field ion microscope (FIM) tips by laser-ion deposition in a high-vacuum environment with an ion extraction voltage of -2 kV. Structural characterization of these films has been carried out by using low-angle x-ray diffraction (XRD) and FIM. The low-angle XRD reveals the formation of an interfacial α-W2C phase. The FIM image indicates the formation of the α-W2C phase on the tungsten tip. X-ray photoelectron spectroscopy has been utilized to reveal that the bonding character in the film is sp3. Further, x-ray-excited Auger electron spectroscopy has also supported the diamondlike nature of the films. The results are discussed, and a sequence of layers deposited on tungsten is suggested in view of the structural match

Theoretical study of the reaction CH(X-2 Pi)+NO(X-2 Pi). 3. Determination of the branching ratios

In this paper, which is the third of a series devoted to the title reaction, we present theoretical calculations of branching ratios for the product channels involved in the reaction. In the first paper of this series (Marchand, N.; Jimeno, P.; Rayez, J. C.; Liotard, D. J. Phys. Chem. 1997, 101, 6077.), we explored the topology of the lowest triplet potential energy surface determined with sophisticated ab initio methods and proposed several reaction paths connecting the reactants to the products. We have used these results to determine the branching ratios using two methods based on multichannel Rice-Ramsperger-Kassel-Marcus (RRKM) calculations: a μVTST/RRKM (μVTST = microcanonical variational transition state theory) method developed by one of us and an ACIOSA/RRKM (ACIOSA = adiabatic capture model using the infinite order sudden approximation) method dealing with a capture rate constant calculation (Marchand, N.; Stoecklin, T.; Rayez, J. C. To be submitted, of this series). Our present results reveal that, at 300 K, HCN + O is the major product channel involved in the reaction (72.0%), the other branching ratios being 13.9% for NCO + H, 8.2% for CO + NH, 3.3% for CNO + H, and 1.4% for CN + OH. All the others channels contribute for less than 1% each. These theoretical results are in agreement with the results of several experimental studies, especially those very recently obtained in our laboratory by Bergeat et al. Moreover, we observe no significant temperature dependence of the branching ratios