Hydrocarbon films

An additional advantage to neutron reflectivity is that high-vacuum conditions are not required. Thus, while studies on solid films can easily be pursued by several techniques, studies involving solvents or other volatile fluids are amenable only to reflectivity techniques. Neutrons penetrate deeply into a medium without substantial losses due to absorption. For example, a hydrocarbon film with a density of Ig cm havii a thickness of 2 mm attenuates the neutron beam by only 50%. Consequently, films several pm in thickness can be studied by neutron reflecdvity. Thus, one has the ability to probe concentration gradients at interfaces that are buried deep within a specimen while maintaining the high spatial resolution. Materials like quartz, sapphire, or aluminum are transparent to neutrons. Thus, concentration profiles at solid interfaces can be studied with neutrons, which simply is not possible with other techniques. 

Richter, F., et al., Preparation and Properties of Amorphous Carbon and Hydrocarbon Films, in Applications of Diamond Films and Related Materials (Y. Tzeng, et al., eds.), Elsevier Science Publishers, pp. 819-826 (1991)... 

Hydrocarbon emissions, polymerization-process, 20 231 Hydrocarbon film, 24 750 Hydrocarbon injectants, in oil recovery, 23 617... 

A hydrophobic Si surface condition is also observed after alkaline treatments, like CMP at a pH of about 11 or after etching in alkaline solutions, as shown in Fig. 2.1b. Hydrophobic Si surfaces are very susceptible to hydrocarbon contamination, for example from the ambient atmosphere or from hydrocarbon films floating on a liquid. To avoid the latter case, water rinses and HF dips are often performed in an overflow wet bench. 

Repulsive van der Waals forces occur in a number of practically important cases, such as for different types of polymers in organic solvents (van Oss et al. 1980) and for certain hydrocarbon films on water (as mentioned in Vignette X). For example, the use of repulsive van der Waals forces has been suggested as a way to dissociate antigen-antibody complexes by van Oss et al. (1979). A much more detailed and quantitative introduction to repulsive van der Waals forces may be found in Israelachvili (1991). 

Optically black hydrocarbon films may be formed in aqueous media from solutions of isosorbide mono-oleate (166i) and its mono(trans-docosenoate) (166j) and phospholipids in decane.262... 

Deuterated hydrocarbon films have been found to be excep-... 

A three-zone DC model for treating electrochemical ET at a self-assembled monolayer (SAM) film-modified metal electrode surface [49] is displayed in Figure 3.27, where zones I, II, and III, defined by parallel infinite planes, correspond, respectively, to an aqueous electrolyte, a hydrocarbon film, and the metal, and the ET-active redox group is represented by a point charge shift (Aq) in a spherical solute cavity [22]. The Poisson equation has been solved for this system, and the results analyzed in terms of image charge contributions to As [22] (see below). 

Annotated version of this same program for computation of van der Waals force of water across a hydrocarbon film of thickness / (written as a MathCad program)... 

The adsorption of hydrocarbon molecules on Si surfaces is an interesting topic of study under various viewpoints. For example, a thin hydrocarbon film coating Si may be applied as a low dielectric in microelectronics and may passivate the surface if covalent bonds are formed between Si atoms and the adsorbate species. Further, unsaturated hydrocarbons play an important role as precursor species for chemical vapor deposition (CVD) of diamond - like films on the Si surface, and of silicon carbide (SiC). 

Table 11.1. Physical properties of hydrocarbon films deposited with a remote electron cyclotron resonance plasma from three different C2Hz source gases at three different dc self-bias voltages 1% np represents the parallel component of the real part of the refractive index as measured by in situ ellipsometry. The film composition is obtained from ion-beam analysis. The total particle number densities nc and n-H are calculated from the stoichiometry and the film thickness. Deposition parameters pressure p = 0.2 Pa adjusted with gas flow at constant pumping speed, absorbed microwave power density P = 10 kW nT3 [17]...

This finding can be explained by referring to the case of chemical erosion of hydrocarbon films by atomic hydrogen the pioneering work of Kiippers and co-workers [53] revealed that the elementary erosion reaction is not a direct... 

W. Jacob Surface reactions during growth and erosion of hydrocarbon films. Thin Solid Films 326, 1 (1998)... 

A. von Keudell, W. Jacob Growth and erosion of hydrocarbon films, investigated by in situ elfipsometry. J. Appl. Phys. 79, 1092 (1996)... 

W. Jacob, W. Moller On the structure of thin hydrocarbon films. Appl. Phys. Lett. 63, 1771 (1993)... 

A. von Keudell Formation of polymer-like hydrocarbon films from beams of methyl radicals and atomic hydrogen. Thin Solid Films 402, 1 (2002)... 

M. Meier A. von Keudell Temperature dependence of the methyl sticking coefficient on hydrocarbon film surfaces. J. Chem. Phys. 116, 5125 (2002)... 

C. Hopf, A. von Keudell, W. Jacob Chemical sputtering of hydrocarbon films by low-energy Ar+ ion and H atom impact. Nucl. Fusion 42, L27 (2002)... 

C. Hopf, W. Jacob, A. von Keudell Ion-induced surface activation, chemical sputtering, and hydrogen release during plasma-assisted hydrocarbon film growth. J. Appl. Phys. (2005) in print... 

Co-deposition of tritium with carbon is potentially the major T repository for ITER even if the use of carbon is minimized to the divertor strike plates. Retention by other mechanisms is expected to be low and to contribute only marginally to the in-vessel tritium-uptake (Sect. 12.4). For this reason the focus here is on some recent experimental findings associated with ( ) carbon erosion and deposition patterns in existing tokamaks, ( ) hydrocarbon film formation in areas of the divertor hidden from the plasma, and (in) mixed-material effects. 

Hydrocarbon Film Formation in Divertor Areas Remote from the Plasma... 

Vigorous R D is in progress in various tokamaks and in laboratory studies to investigate hydrocarbon film formation. The main results can be summarized as follows ... 

K. Gibson, The removal of co-deposited hydrocarbon films from plasma facing components using high-powr pulsed flash lamp irradiation, J. Nucl. Mater, in press... 

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