Hiroyuki Tawara

Energy dependence of the ion-induced sputtering yields of monatomic solids

Abstract The ion-induced sputtering yields of monatomic solids are presented graphically for various ion-target combinations as a function of the energy of normally incident ions. Each graph shows the available experimental data points for an ion-target combination and the energy dependence of the sputtering yield calculated from an empirical formula whose parameters were determined by the best fit to available data. The method of calculating the sputtering yields for any ion-target combination based upon the empirical formula is also described.

Total and partial ionization cross sections of atoms and ions by electron impact

Abstract Experimental data on electron impact ionization cross sections for atoms and ions ranging from H to U are compiled and given, in graphical form, as a function of the electron impact energy. Someselected theoretical data are also included. The literature is surveyed up to mid-1986.

Equilibrium charge state distributions of ions (Z1≥4) after passage through foils: compilation of data after 1972

Tables are presented for equilibrium charge distributions, mean charges, and distribution widths of energetic heavy ions (Z/sub 1/> or =4) passing through thin foils. Data reported since May 1972 are included here, updating tables compiled by Wittkower and Betz in AtomIc Data 5, 113 (1973).

Cross sections for electron capture and loss by positive ions in collisions with atomic and molecular hydrogen

Experimental cross sections for electron capture and loss by atomic positive ions in collisions with atomic and molecular hydrogen targets are tabulated as a function of the incident energy of projectile ions and of their charge state. Literature up to mid-1984 has been covered.

Unified empirical formulas for the backscattering coefficients of light ions

Abstract Empirical formulas for the number- and energy-backscattering coefficients of light ions normally incident on elemental solid targets are given. The formulas are valid for all the light ions of atomic numbers up to two with incident energies from about 10 eV to 100 MeV. Constants in the formulas have been determined by the least-squares fit to available experimental and selected computer-simulation data. The rms deviation of the data from the formulas is 31%.

Empirical formulas for the backscattering coefficients of light ions obliquely incident on solids

Abstract The dependence on the angle of incidence θ of the number-backscattering coefficient Rn and the energy-backscattering coefficient Re of H, D and He ions has been found to be fitted by the expression R(θ)=R(0°) + [1-R(0°)]/(1 +A1 cot2A2θ), where R represents either Rn or RE and the parameters At (i = 1,2) are functions only of the Thomas-Fermi reduced energy e. By using the semiempirical formulas of Tabata et al. for R(0°), universal formulas for R(θ) have been obtained These formulas are valid for all the mass regions of the target atom and for 2 × 10–2 ≲ e ≲ 10.

Database and retrieval-display system for compiled sputtering data

Abstract Data on the sputtering yields of monatomic solids have been compiled as one of the activities in the Research Information Center, Institute of Plasma Physics, Nagoya University. Further, a computerized database and a retrieval-display system for the sputtering yields have been constructed. Numerical data with the relevant bibliographic notations can be retrieved by keywords such as authors.incident ions, target materials etc. on the on-line system. After retrieval, data can be out-put on a graphic display terminal and also printed in a graphical form as a function of the energy of an incident ion. This system is demonstrated during the Conference.

State-selective one-electron capture from H and H2 by slow, highly stripped C, N, O and Ne ions

One-electron capture processes of highly stripped ions of Neq+(q=8, 9), Oq+(q=6-8), Nq+(q=5-7) and Cq+(q=4-6) in slow collisions with H atoms and H2 molecules have been investigated. The final-state distributions of product ions are analysed using translational energy spectroscopy at a collision velocity of about 600 eV amu-1, which is much slower than 1 au. The electron is selectively captured into a single n shell in all the systems except for Ne9+-H2, O7+-H2 and N7+-H2 systems, where two n shells are populated with comparable fractions. The observed selectivity is explained by using the simple Landau-Zener mode.

Electron capture in Iq+ (q = 10–41) + He collisions at low energies

One electron capture processes in Iq+ (q = 10–41) +He collisions at low energies have been investigated. It is found that total cross sections for one-electron capture processes increase roughly linearly with increasing charge q of the incident ions and also increase with the square of the crossing radius Rc of the diabatic potential energy curves where the electron transfer takes place. These smooth increases are in contrast to those observed for ions with low charge q < 10.

Electron transfer into selective excited states in collisions of highly stripped C, N, O and Ne ions with H and H2

Abstract The final state distributions have been determined by the method of translational energy spectroscopy in slow collisions of highly stripped C q + ( q =4–6), N q + ( q =5–7), O q + ( q =6–8), and Ne q + ( q =8,9) ions with atomic and molecular hydrogen. The observed state-selectiveness is discussed on the basis of the classical overbarrier model and the Landau-Zener model.