Heavy Ion Scattering

These INS studies of the alkali metal hydrides provide an excellent example of the careful analysis of INS experimental data. It includes the application of corrections for multiple scattering, neutron absorption and heavy-ion scattering the extraction of quantities related to the hydrogen dynamics (the hydrogen mean square displacement, mean kinetic energy and the hydrogen Einstein frequency) and provided the density of vibrational states for each type of atom, shown individually and ab initio modelling of the full INS spectra. 

Frahn, W.E. Generalized Fresnel model for very heavy ion scattering. Nucl. Phys. A302, 267-280 (1978)... 

Figure 4.15 Schematic representation of RBS. Top the incident ions are directed such that they either scatter back from surface atoms or channel deeply into the crystal. Middle the ions scatter back from target atoms throughout the outer micrometers and suffer inelastic losses, causing the energy of the backscattered ions to tail to zero. Bottom scattering from the heavy outer layer gives a sharp peak separated from the spectrum of the substrate as in the middle diagram.

Hydrated electron yields decrease with increasing MZ jE, but they do not seem to decrease to zero. Experiments have been performed on aerated and deaerated Fricke dosimeter solutions using Ni and ions [93]. One half of the difference in the ferric ion yields of these two systems is equal to the H atom yield. The Fricke dosimeter is highly acidic so the electrons are converted to H atoms and to a first approximation the initial H atom yield can be assumed to be zero (see below). There is considerable scatter in the data of the very heavy ions, but they seem to indicate that hydrated electron yields decrease to a lower limit of about 0.1 electron/100 eV. The hydrated electron distribution is wider than that of the other water products because of the delocalization due to solvation. This dispersion probably allows some hydrated electrons to escape the heavy ion track at even the highest value of MZ jE. 

Fig. 13 gives the results of several studies on the measurement of H2O2 with heavy ions [26,45,116,126,132,133]. The yield of H2O2 never varies significantly from its value with fast electrons and -rays. There is a significant amount of scatter in the data so predicting trends is difficult. Large scatter in the data is expected for yields determined by material... 

Reactions of atomic carbon, produced by nuclear reactions, with a number of hydrocarbons have been studied by Wolfgang and his collaborators (69). To minimize radiation induced secondary reactions which occur when use is made of C14, a technique has been developed using short-lived C11 produced by a neutron exchange reaction between a platinum foil and a C12 ion beam from a heavy ion accelerator. Part of the scattered Cu atoms has been allowed to penetrate through the thin brass foil wall of a brass vessel and come in contact with the compound wrhose reaction is studied. Products have been analyzed by gas chromatography using a technique of simultaneous mass and radioactivity determination. 

Fig. 12. Schematic diagram of metal binding by human CCS. hCCS domains 1, 2, and 3 are labeled with roman numerals. Cysteine residues are designated as S. The disulfide bond in domain 2 is indicated by S-S. (a) Cobalt binding to hCCS. Electronic absorption spectra indicate that two equivalents of Co(II) bind per hCCS monomer, one through three or four cysteine residues in a tetrahedral geometry, and one with a geometry similar to that found in the zinc site of SODl (see text) (Zhu et al., 2000). (b) Copper binding to hCCS. XAS indicates that two Cu(I) ions bind per hCCS monomer in a sulfur-only liganding environment, with an additional heavy atom scatterer peak suggesting the presence of a /t2-bridged dicopper cluster (Eisses et al., 2000).

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