Gas-phase functionalization

Several years ago the concept of near-surface imaging was introduced(l,2). The critical step that imparts the etch selectivity by introduction of refractive elements is termed gas-phase functionalization and involves the selective reaction... 

Figure 1. Gas phase functionalization scheme for single-layer resists.

Etch selectivity is crucial to the gas-phase functionalized resist schemes. Since the thickness of the etch resistant Ti02 layer that forms on the polymer film should depend on the amount of water sorbed on the polymer surface, we studied the influence of various processing parameters on the surface water content as measured by the amounts of Ti deposited. 

Photooxidative imaging scheme using the gas-phase functionalization of hydrophilic polymer regions by TiCl4 treatment and 02 RIE development. 

G.N. Taylor, L.E. Stillwagon, and T. Venkatesen, Gas phase functionalized plasma developed resists Initial concepts and results for electron heam exposure, J. Electrochem. Soc. 131, 1658 (1984). 

G.N. Taylor, L.E. Stillwagon, and T. Venkatesen, Gas phase functionalized plasma developed resists Initial concepts and results for electron beam exposure, J. Electrochem. Soc. 131, 1658 (1984) M.A. Hartney, R.R. Kunz, D.J. Ehrlich, and D.C. Shaver, Silylation processes for 193 nm excimer laser hthography, Proc. SPIE 1262, 119 (1990) M.A. Hartney and J.W. Thackeray, Sily lation processes for 193 nm lithography using acid catalyzed resists, Proc. SPIE 1672, 486 (1992) ... 

Figure 9.9 Illustration of the setup used for (a) liquid phase, where the CNTs are treated at the same temperature in the presence of the oxidizing agent, and (b) gas-phase functionalization of CNTs where the pretreatment temperature of the CNTs can be tuned with respect to the temperature of the oxidizing chemical agent.

The simulated distillation method uses gas phase chromatography in conjunction with an apolar column, that is, a column where the elution of components is a function of their boiling points. The column temperature is increased at reproducible rate (programed temperature) and the area of the chromatogram is recorded as a function of elution time. 

These concluding chapters deal with various aspects of a very important type of situation, namely, that in which some adsorbate species is distributed between a solid phase and a gaseous one. From the phenomenological point of view, one observes, on mechanically separating the solid and gas phases, that there is a certain distribution of the adsorbate between them. This may be expressed, for example, as ria, the moles adsorbed per gram of solid versus the pressure P. The distribution, in general, is temperature dependent, so the complete empirical description would be in terms of an adsorption function ria = f(P, T). 

Another technique employs a database search. The calculation starts with a molecular structure and searches a database of known spectra to find those with the most similar molecular structure. The known spectra are then used to derive parameters for inclusion in a group additivity calculation. This can be a fairly sophisticated technique incorporating weight factors to account for how closely the known molecule conforms to typical values for the component functional groups. The use of a large database of compounds can make this a very accurate technique. It also ensures that liquid, rather than gas-phase, spectra are being predicted. 

Phofoelectron spectroscopy is a simple extension of the photoelectric effect involving the use of higher-energy incident photons and applied to the study not only of solid surfaces but also of samples in the gas phase. Equations (8.1) and (8.2) still apply buf, for gas-phase measuremenfs in particular, fhe work function is usually replaced by fhe ionization energy l so fhaf Equation (8.2) becomes... 

NTU p is the "exterior apparent" overall gas-phase number of transfer units calculated neglecting axial dispersion simply on the basis of equation 56, whereas NTU stands for the higher real number of transfer units (Nq ) which is actually required under the influence of axial dispersion. The correction factor ratio can be represented as a function of those parameters that are actually known at the outset of the calculation... 

In order for a soHd to bum it must be volatilized, because combustion is almost exclusively a gas-phase phenomenon. In the case of a polymer, this means that decomposition must occur. The decomposition begins in the soHd phase and may continue in the Hquid (melt) and gas phases. Decomposition produces low molecular weight chemical compounds that eventually enter the gas phase. Heat from combustion causes further decomposition and volatilization and, therefore, further combustion. Thus the burning of a soHd is like a chain reaction. For a compound to function as a flame retardant it must intermpt this cycle in some way. There are several mechanistic descriptions by which flame retardants modify flammabiUty. Each flame retardant actually functions by a combination of mechanisms. For example, metal hydroxides such as Al(OH)2 decompose endothermically (thermal quenching) to give water (inert gas dilution). In addition, in cases where up to 60 wt % of Al(OH)2 may be used, such as in polyolefins, the physical dilution effect cannot be ignored. 

Radial density gradients in FCC and other large-diameter pneumatic transfer risers reflect gas—soHd maldistributions and reduce product yields. Cold-flow units are used to measure the transverse catalyst profiles as functions of gas velocity, catalyst flux, and inlet design. Impacts of measured flow distributions have been evaluated using a simple four lump kinetic model and assuming dispersed catalyst clusters where all the reactions are assumed to occur coupled with a continuous gas phase. A 3 wt % conversion advantage is determined for injection feed around the riser circumference as compared with an axial injection design (28). 

The low DOS achieved in i -Si H enables it to be readily doped, a prerequisite for any device appHcation n- and -type doping is achieved by the addition of PH and B2H to SiH in the gas phase, respectively. Figure 3, a plot of and conductivity activation energy, AH, as a function of PH and 2 6 content, shows that the most heavily f -type doping results in (Hem). By manipulating the plasma (using SiF and H2) or heavily diluting... 

In this process the addition of water vapor to the sweep stream can be controlled so that the water activity of the gas phase equals that of the beverage. When this occurs, there is no transport of water across the membrane. The water content of both the beverage feed and the sweep stream is kept constant. These conditions must be maintained for optimum alcohol reduction. The pervaporation system controls the feed, membrane, airstream moisture level, and ethanol recovery functions. An operational system has been developed (13). 

Section 4.04.1.2.1). The spectroscopic and the diffraction results refer to molecules in different vibrational quantum states. In neither case are the- distances those of the hypothetical minimum of the potential function (the optimized geometry). Nevertheless, the experimental evidence appears to be strong enough to lead to the conclusion that the electron redistribution, which takes place upon transfer of a molecule from the gas phase to the crystalline phase, results in experimentally observable changes in bond lengths. 

Typical methods are those of F. C. Zevnik and R. L. Buchanan [Chem. Eng. Progi , 59, 70-77 (Feb. 1963)] and J. H. Taylor Eng. 6-Proc. Econ., 2, 259-267, 1977). The former is mainly a graphical method of estimating the cost per functional unit (Cp) based on the capacity, the maximum pressure, the maximum temperature, and the materials of construction. The Taylor method requires the determination of the costliness index, which is dependent on the complexity of the process. A simpler method was suggested by S. R. Timms (M.Phil. thesis, Aston University, England, 1980) to give the battery hmits cost for gas phase processes only in U.S. dollars with a Marshall and Swift index of 1000. The simple equation is... 

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