Hot atom reaction

Shalashilin D V, Jackson B and Persson M 1999 Eley-Rideal and hot atom reactions of H(D) atoms with D(H)-covered Cu(111) surfaces quasiclassical studies J. Chem. Phys. 110 11 038... 

Hot atom reactions have also been used to label organic compounds with T. Irradiation of helium-3 with neutrons according to the nuclear reaction produces very energetic tritium atoms that can displace ordinary hydrogen in organic compounds. This procedure is not very selective, and the labeling pattern must be determined to enable the tritiated product to be used effectively as a tracer (34). 

Recent work (51) on FeCpj irradiated in Fe(CO)5 solutions (to give FeCpj) has shown that the Fe atom can come from the Fe(CO)j molecule. The mechanism is unknown and may well involve exchange or other reactions in solution in addition to hot atom reactions. The results do show, however, that it is not necessary to preserve the Fe-Cp bonding in order to reform FeCpj. In frozen solutions the yield of FeCpj is much lower than in liquid solutions. 

Contents Introduction. - Experimental Techniques Production of Energetic Atoms. Radiochemical Separation Techniques. Special Physical Techniques. - Characteristics of Hot Atom Reactions Gas Phase Hot Atom Reactions. Liquid Phase Hot Atom Reactions. Solid Phase Hot Atom Reactions. - Applications of Hot Atom Chemistry and Related Topics Applications in Inorganic, Analytical and Geochemistry. Applications in Physical Chemistry. Applications in Biochemistry and Nuclear Medicine. Hot Atom Chemistry in Energy-Related Research. Current Topics Related to Hot Atom Chemistry and Future Scope. - Subject Index. 

It should be unaffected by the presence of Cl2 and Br2, which could not compete effectively with these reactions at the halogen HC1 ratios shown in Fig. 5(a) and (b). Thus hot atom reactions can account for the residual (or unscavengeable) hydrogen, GH = 2.2, as well as contribute to the yield of scavengeable hydrogen atoms. 

In addition to the fully LH reaction of + CO, C02 apparently produced by hot atoms is also observed by thermal dissociation [367], photochemical dissociation [368,369] or collisional dissociation [370] of 02 co-adsorbed with CO. Dosing a CO adsorbed layer with gas phase atoms also appears to give the same hot atom reaction, i.e., reaction prior to the atom fully equilibrating with the surface [371]. In all cases, the oxidation occurs at Ts far below the thermal LH... 

Eley-Rideal and hot atom reactions between H atoms on metal and graphite surfaces... 

Kiippers and co-workers have successfully used the random walk form to reproduce the behavior observed on Cu(l 11), Pt(lll) and Ni(l 0 0) [26]. They demonstrate that the different behaviors with regard to the short time (pre-saturation) HD formation rates can be explained in terms of the relative rates of hot atom reaction and sticking. We have used our kinetic equations to derive approximate analytical expressions for initial reaction rates and product yields as a function of the initial surface coverage, and these have compared well with the experimental findings of the Kiippers group [37]. 

Reactions Formation of non- equilibrium alloys Syntheses of non-conventional compounds Simulation of Hot Atom reactions... 

B. H -I- CO2 Hot-Atom Reactions Under Single-Collision, Arrested-Relaxation Conditions... 

The distribution of cyclohexadienyl radical isomers formed fiom toluene by addition of Mu, thermal or nominally hot T is very similar, suggesting that the conditions of formation are not significantly different (Table 1). In all cases addition in the ortho position occurs with higher than statistical probability, at cost of the other positions. The methyl substituent in toluene thus has a clear ortho-directing effect. Cl, F and CF3 are meta-directing, and phenoxy, COCl and CN are para-directing [12]. For hot atom reactions one normally expects a statistical distribution. 

Hot atom reactions can be used for synthesis of labeled compounds. So far this technique has been used primarily for and labeling. For example, an organic gaseous conqx)und is mixed with He and the sample is irradiated with neutrons. The reaction He(n,p) H produces tritium as hot atoms (indicated by the small arrow) with kinetic ergies of approximately 0.2 MeV. These hot atoms react with the organic molecules to produce labeled compounds. An example is the formation of labeled butanol... 

The most successful means for studying monomeric SiF2 has been via hot atom reactions in which nudeogenic silicon atoms abstract two fluorine atoms from their PFg precursor (9-11). 

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