Deuterium ions

The quantitative effect of the mass, energy, and angle of impact on the sputter yield for impacting deuterium ions is shown in Figs. 12a and b. As the kinetic energy... 

Second, metabolism of 6-fluoroBP by rat liver microsomes yields the same BP quinones obtained in the metabolism of BP (23). This suggests that these products are formed by an initial attack of a nucleophilic oxygen atom at C-6 in the 6-fluoroBP radical cation with displacement of the fluoro atom. In fact, when 6-fluoroBP is treated with the one-electron oxidant Mn(0Ac)3, the major products obtained are 6-acetoxyBP and a mixture of 1,6- and 3,6-diacetoxyBP (15), indicating that reaction occurs via an initial attack of acetate ion at C-6 of the 6-fluoroBP radical cation. On the other hand electrophilic substitution of 6-fluoroBP with bromine or deuterium ion shows no displacement of fluorine at C-6, although in both cases substitution occurs at C-l and/or C-3. These results indicate that... 

The study was subsequently extended to include the radiofluorodemetallation of organogermanium compounds31. Both fluorine-18 and 18F-acetylhypofluorite were used to displace the trimethylgermyl moiety from a series of para-substituted aryltrimethyl-germanes (equation 26). The 18F was produced in a cyclotron by bombarding Ne atoms with deuterium ions (equation 27). 

Hyd ron The hydrogen ion, is generally referred to as the proton, which is the nucleus of hydrogen, H. But since hydrogenase can also use deuterium ions (deuterons, and tritium ions (tritons, as substrates, the correct term is hydrons , which does not discriminate between the isotopes. 

The inversion, with or without invertase or acid, has also been useful in studying the chemical effect of the deuterium ion, of high pressure, of sonic and supersonic energy of ultraviolet light " of high-frequency electric energy and of variation in the dielectric constant of the solvent. ... 

Isotopes of masses 248, 249, 250, 251 and 252 may be prepared from berkeh-um-249 or californium-249 by bombardment with alpha particles or deuterium ions ... 

Miller and Ishida [11] combined size-exclusion chromatography with diffuse reflectance FUR -spectroscopy to identify the hydrolysis and condensation products of phenyltriethoxysilane in mixed organic-aqueous media. Pohl and Osterholtz [8, 12] followed the condensation of alkylsilanols using 3C- and 29Si-NMR spectroscopy and found condensation to be catalyzed by both deuteroxide anion and deuterium ion. Savard etaL [13] used H-NMR spectroscopy to follow the rate of hydrolysis and condensation of 3-methacryloxypropyltrimethoxy-silane as a function of the pH. These authors used the Lentz technique of derivatization to determine the structures of some of the condensation products. 

Apparently, experiments with labeled proton donor (e.g. CD3 or COOD) should be implemented. Then the reaction of deuterium ions will produce the expected labeled water in the respiratory process, which will unambiguously indicate the validity of the suggested mechanism. 

Desorption yields for the three above mentioned processes can be combined with the expected particle fluxes to give estimates of the impurity influx for these desorption processes. The corresponding impurity influx from deuterium ion impact desorption is estimated to be about two orders of magnitude larger than that expected from either electron or photon induced desorption. Therefore, the impurities released into the plasma during a short discharge ( 1 s) will be dominated by deuterium impact desorption while electron and photon induced desorption will occur only to a much more limited extent. 

The diimine protons absorb at very low field (-4 to —6t, Table 5) and are therefore easily exchanged by deuterium ions. In the presence of catalytic amounts of a strong base N2H2[Cr(CO)5 ]2 irreversibly disproportionates to N2[Cr(CO)s]2 and N2H4[Cr(CO)5]2 60>. 

Three types of ion sources are in common use. The radio frequency ion source 28> has advantages of a high (70—90%) atomic deuterium ion beam, high stability, and low deuterium gas consumption. This source is, however, very sensitive to impurities in the deuterium gas and requires... 

The cross section for the 3H(maximum value at only 107 KeV incident deuteron energy. When thick ( 1 mg cm-2 thick deposit of titanium) titanium-tritium targets are used, however, the neutron yield continues to increase even above 200 KV acceleration potential. This is due to increased penetration of the deuteron beam into the tritium enriched layer. Since the penetration of molecular deuterium ions is less than that for monatomic deuterium ions for the same acceleration potential, accelerators using Penning ion sources require extremely clean vacuum systems to minimize build-up of deuteron absorbing deposits on the surface of the target. 

Ionization of Acetylene. Acetylene is known to possess acidic properties and when it is shaken with heavy water the density of the latter becomes less in alkaline solution indicating an exchange between the hydrogen of the acetylene and the deuterium ions of the water. The exchange does not take place with measurable velocity in acid solutions where the dissociation of the weak acetylene acid is repressed. 

These radionuclides are produced by irradiating targets with beams of hydrogen ions (protons), but frequently deuterium ions (deuterons) are used (see Table 21.10). Some products require beams of helium-4 and helium-3 ions. The typical process involves the capture of the proton with the prompt emission of a neutron. This is called a p,n reaction. However, in other cases there may be protons, alpha particles, or up to five neutrons emitted. The resulting products decay generally by positively charged electron (positron) emission, but also decay by capture of an orbital electron. 

J.W. Davis, A.A. Haasz, Thermal desorption of graphite during deuterium ion bombardment, J. Nucl. Mater. 217 (1994) 206... 

G. Hansali, J.B. Biberian, M. Bienfait, Ion beam implantation and thermal desorption of deuterium ion in graphite, J. Nucl. Mater. 171 (1990) 395... 

Beryllium exhibits an interesting fluence dependent hydrogen retention behavior. During low fluence exposures of beryllium to deuterium ion beams,... 

Of course, oxygen is not the only impurity that will react with beryllium. Another material that is important in forming mixed-material layers with beryllium is carbon. The saturated value of retention that has been found in beryllium surfaces exposed to a large deuterium ion fluence could easily be overshadowed if a carbon rich layer forms on the beryllium surface due to impurity carbon ions in the incident plasma flux. The hydrogen retention properties of plasma deposited carbon films has been shown to dominate the total retention in beryllium samples exposed to the plasma at lower temperature. Once the sample temperature during exposure approaches 500°C there is little difference between the retention in Be/C mixed-material layers compared to clean beryllium samples [48]. The temperature dependence of the retention of carbon containing mixed material layers, as well as that of clean beryllium surfaces is shown in Fig. 14.10. There are two possible explanations for the reduced retention in the mixed-material layers formed at elevated temperature. The first is that beryllium carbide forms more readily at elevated temperature and less retention is expected in beryllium carbide [11]. The second is that carbon films deposited at elevated temperature also tend to retain less hydrogen isotopes [49]. 

Messmer and Sziman measured the coupling rates of p-methoxybenzene-diazonium tetrafluoroborate with N,N-dimethylaniline, m-toluidine and 1- and 2-naphthylamine in nitrobenzene as solvent. Except for reactions with m-toluidine, the reaction rates were reduced significantly if a deuterium ion had to be displaced instead of a proton. The kinetic isotope effect varied from k /kp = 1.5 for 2,4,6-dj-... 

The proton is indeed anomalous in its conductance and mobility. These properties do not vary with temperature in the expected, regular way. There is not the expected near-sameness for hydronium and deuterium ion mobilities. The conductance of protons in aqueous-non-aqueous media is wholly dependent on the mole-fraction of water present. 

The reaction of metals with energetic hydrogen or deuterium ions is important in nuclear reactors. Ion beams may be generated thermally and allowed to interact with the metal, and the reaction products then may be examined by matrix-isolation techniques. Alternatively, metal atoms are sputtered from a cathodic surface by a low-energy plasma. If or at low P is added to the discharge, then molecular species are formed by the interaction with the sputtered metal atoms. Applied to Cu this technique leads to the identification of CuH and CuD in Ar matrices by their IR spectra. The reacting species are believed to be atomic Cu and H or D formed in the hollow-cathode discharge . 

Their unique relation to water systems favors the inclusion of acid-base reactions in deuterium oxide with aqueous acid-base equilibria, even though some aspects of the chemistry suggest inclusion with nonaqueous solvents. In studies such as those of deuterium isotope effects, it is desirable to be able to measure pD as an index of acidity in heavy water. Glass electrodes respond in a nemstian way to changes in deuterium ion concentration, and therefore the usual combination of glass and calomel electrodes can form the basis of an operational definition of pD ... 

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