Binary reactions

Deposition of Si02 has been achieved by exposing the substrate to the binary reaction sequence SiCL-l-2H20 —> Si02+ 4HC1. This is divided into the following half-reactions in which species at the surface are inaicated by asterisks [95] ... 

George S M, Sneh O, Diiion A C, Wise M L, Ott A W, Okada L A and Way J D 1994 Atomic iayer controiied deposition of SiO, and Ai,0, using ABAB.. . binary reaction sequence chemistry Appl. Surf. Sc/. 82/83 460-7... 

Ott A W, McCariey K C, Kiaus J W, Way J D and George S M 1996 Atomic iayer controiied deposition of Ai203 fiims using binary reaction sequence chemistry App/. Surf. Sc/. 106 128-36... 

Ott A W, Kiaus J W, Johnson J M and George S M 1997 Ai203 thin fiim growth on Si(IOO) using binary reaction sequence chemistry Thin Solid Films 292 135-44... 

Use chemical interaction matrices to identify potential incompatibilities between combinations of materials (not just binary reactions) and interactions with cleaning solvents, heat transfer fluids and other utilities, equipment lubricants, scrubbing media, materials of construction, etc. Implement management of change procedures for changes in design, operation, equipment and chemistry. 

The simplest solid—solid reactions are those involving two solid reactants and a single barrier product phase. The principles used in interpreting the results of kinetic studies on such systems, and which have been described above, can be modified for application to more complex systems. Many of these complex systems have been resolved into a series of interconnected binary reactions and some of the more fully characterized examples have already been mentioned. While certain of these rate processes are of considerable technological importance, e.g. to the cement industry [1], the difficulties of investigation are such that few quantitative kinetic studies have been attempted. Attention has more frequently been restricted to the qualitative identifications of intermediate and product phases, or, at best, empirical rate measurements for technological purposes. 

For the situation denoted by the solid lines in Figure 1, the only possibilities for AB+ + CD are denoted by the left-hand side of the potential surface since this is completely decoupled from the right-hand side. On the right-hand side, as illustrated, the association of AC+ + BD to produce AC+ BD and ACBD+ is analogous to the left-hand side. However, an additional part of the potential surface is illustrated where the reactants A+ + CBD (dot-dashed line) are also shown to access the ACBD+ well. Thus, these reactants are directly coupled to AC+ + BD and the binary reaction,... 

In the following sections, studies of isomeric ions are reported in which the ions are reactively probed. Where calculations are available, information on potential energy surfaces is given. This is usually the structure of the stable isomeric forms and transition states and their relative energies thus only points on the potential surface are known. The detailed form of the potential surface is almost never available nor is the connectivity between the various states usually established theoretically (chemical intuition is often used to connect the states). Pertinent experimental data on CID and metastable ions, isomers produced in binary reactions, and potential surfaces probed by binary reactions (with the excited isomeric ion as the reaction intermediate) are also given. 

Other isomeric forms can be created in binary reactions such as,... 

Figure 4. Part of the potential energy surface of CHsO+ calculated by Chunxiano et al.69 (solid lines) and constructed from thermochemical data in the literature.27-30 The dashed lines indicate that the connected species are coupled by binary reactions, as determined experimentally. It is not meant to imply that there are no barriers between...

Isomers of C2H50+ have also been accessed by the binary reactions,24,25 ... 

The foregoing discussions have shown how valuable ion-molecule reactions are in probing potential energy surfaces of isomers, ABCD+, by accessing the surface with association reactions, transiently with binary reactions where essentially the (ABCD+) intermediate undergoes unimolecular decomposition, or as a product in binary reactions. In the association reactions, isomers can only be produced if they... 

The master equation approach considers the state of a spur at a given time to be composed of N. particles of species i. While N is a random variable with given upper and lower limits, transitions between states are mediated by binary reaction rates, which may be obtained from bimolecular diffusion theory (Clifford et al, 1987a,b Green et al., 1989a,b, 1991 Pimblott et al., 1991). For a 1-radi-cal spur initially with Ng radicals, the probability PN that it will contain N radicals at time t satisfies the master equation (Clifford et al., 1982a)... 

A minimal model for self-replication is shown in Scheme 12.23. The replicator (R) must be able to recognise and bind at least two different precursor components (Cl and C2) in a ternary (three component) complex, and to accelerate their chemical reaction with each other to produce a product that is a copy of the original R. Such a simple system will always be in competition with the uncatalysed binary reaction of Cl and C2. 

The ternary reactions (32) and (33) sequentially build up the NO+ hydrates until N0+(H20)3 is produced, which then undergoes a binary reaction to give the hydrated hydronium ions. Further increases in the size of the hydrates is considered to be via direct clustering ... 

In the higher pressure and low temperature environments of the stratosphere and troposphere, ternary association reactions can proceed very rapidly. Reactions (4b), (4c), (15-17), (22-25) rapidly convert the primary ions to 02 predominantly but with smaller concentrations of NO+ and N02 [via reaction (24b)]. These ions will then be converted to cluster ions via reaction schemes65, 174) analogous to the D-region schemes outlined above. The 02 is first converted to the 02 H20 via reactions (7) and (8), then the binary reaction sequence ... 

In order to solve these equations, we have to be able to evaluate cpj, the species net production rate as a function of conditions and gas composition. If we assume only binary reactions and an Arrhenius temperature dependence for the forward rate coefficients of such reactions, then we can express < j in a reasonably simple form. 

However, encounter theory is subdivided into IET, MET, and DET/UT, and neither of them is perfect. IET is in fact the most universal and general approach to binary reactions in three-dimensional space at low concentration of reactants. Moreover, this is a common limit for all other theories valid at higher concentrations. IET is applied to contact and distant reactions, both reversible and irreversible, and is especially suited for analytic calculations of quantum... 

Koo, Y. and Kopelman, R., Space- and time-resolved diffusion-limited binary reaction kinetics in capillaries. Experimental observation of segregation, anomalous exponents and depletion zone, Journal of Statistical Physics, Vol. 65, 1991, pp. 893-918. 

If, for example, the formation of H2 molecules is computed, all possible binary reactions between different molecules, atoms, ions, photons, etc. have to be considered. This yields according to the above-mentioned definitions, a set of steady state equations which involve the rate constants and the densities of the various reactants. The latter quantities are then computed under the assumption of known rate constants. 

Sample Size. A standardized sample size of 0.075 mmole of reactant was chosen. In a binary reaction system the total sample comprises 0.15 mmole. These amounts provide a convenient sample for analysis and are considered to be safe in the event of an explosion in the 2-ml. reaction vessel. 

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