Light Ions In Solids Research Articles

Analytical Theory of Reflection of Hydrogen Isotopes of Thermonuclear Energies from Construction Materials

A theoretical description of reflection of hydrogen isotopes from a solid body based on data available in modern literature on the cross sections for elastic and inelastic scattering of ions is presented. The results of the analytical calculation are compared with the results of computer simulation and experimental data. The interaction of hydrogen isotopes with energies from 300 eV to 25 keV with materials in a wide range of atomic numbers, namely Be, C, Ti, Ni, W, Au, is considered. A critical review of existing analytical models of multiple scattering of light ions in solids is performed.

Reflection coefficients of light ions for the inverse-square interaction potential

The linear Boltzmann transport equation for diffusion and slowing down of low-energy light ions in solids is Laplace-transformed in relative path-length and solved by applying the DP0 technique. The ion–target atom interaction potential is assumed to have a form of the inverse-square law and furthermore, the collision integral of the transport equation is replaced by the P 3 approximation in angular variable. The approximative Laplace-transformed solution for the reflection function is found and inverted leading to the distribution of backscattered particles in the relative path-length. Analytic expressions for the particle and energy reflection coefficients were derived and our results are compared with a large number of computer simulation data.

Angular dependence of the energy loss of ions in solids: Computer simulations and analysis of models

The angular dependence of the electronic energy loss of light ions in solids is analyzed in the frame of the binary collision approximation (BCA) using an analytical formalism based on multiple scattering (MS) functions, as well as with Monte Carlo (MC) simulations. These simulations have been performed for different collisional models of ions in the solid. A variation of the mean number of collisions with the observation angle is found, for a frequently used random distribution of interatomic distances, which may originate an angular dependence of the energy loss. Additionally the effect of impact parameter restrictions has been investigated, and again a change in the mean number of collisions with the observation angle has been observed. As this variation depends on the model of the solid and the impact parameter criteria applied, uncertainties in the single collision energy loss appear.

Dynamic screening, charge states and energy loss of ions in solids

The stopping power for light ions in solids is discussed by considering the dynamic screening of the moving ion and its charge states as a function of the ion velocity. Taking into account three different mechanisms for the electron capture and loss, the charge states for H and He moving in Al have been calculated introducing the contributions of the ion charge states and the capture and loss processes. Good agreement with experimental data is found.

Mean projected ranges of light ions in solids from anew stopping power equation

Abstract We show that the use of a recently derived, simple and accurate, universal equation for the electronic stopping of ions in solids, together with a simple projected range algorithm (PRAL) derived by Biersack, leads to an easy and reliable means to evaluate projected ranges of ions in solids for non-relativistic velocities. The mathematical simplicity, accuracy and physical clarity in using these two formalisms makes them very useful in practice. Good agreement is observed with experiment and with calculations based on transport theory.

The Transient Magnetic Field and Measurements of g-Factors for High-Spin Rotational States

The systematics of present transient field data are briefly reviewed. The contribution to the field from bound polarized s-electrons and scattering of polarized electrons are discussed. The transient field is compared to measured K-vacancy fractions for light ions in solids, and a mechanism for polarizing the bound electrons of the ions is suggested. This mechanism predicts that the transient magnetic field might decrease for velocities higher than ∼ 10 ν0. Examples of the utilization of the strong transient magnetic field in nuclear g-factor experiments are presented by recent results from measurements of g-factors for high-spin rotational states in deformed nuclei.

An improved method for measuring relative stopping powers of light ions in solids

An improved method is presented for measuring relative stopping powers of light ions in solids by means of Rutherford backscattering. Special care has been taken to obtain low-background spectra, and a procedure (to measure a given sequence of targets again and again) has been used to avoid uncertainties in beam normalization. The target composition can be investigated in situ. Measured stopping-power ratios between copper and silver for 200–2000 keV hydrogen and helium agree with semiempirical tabulations. Results for lanthanum stopping powers are presented to demonstrate the applicability of the method to highly reactive materials.

Diffusion studies by means of nuclear reaction depth profiling

The nuclear reactions D(d, p)T and 6Li(d, α) 4He have been used to study the diffusion of light ions in solids. New techniques are described which allow the derivation of the diffusion coefficients from depth profile measurements. The results show a drastic influence of radiation damage on the diffusion of implanted ions, whereas results on deuterium which has been dissolved from the gas phase agree well with extrapolated data from classical diffusion measurements.

Charge exchange to the continuum for light ions in solids

Electron capture into ionized states of fast ions (H+, H2+, He+) in carbon and gold foils is investigated. Velocity of ejected electrons are measured in the forward direction and a characteristic cusp-shaped peak is found for electrons ejected with velocity equal to that of the incoming ions. The spectra are interpreted by a theory of charge exchange to the continuum, based on an atomic physics ion-atom collision model. As with proper charge exchange, a second order Born approximation is necessary to calculate the high energy cross sections.

Monte Carlo Simulations of the Behavior of Energetic Light Ions in Solids

Monte Carlo Simulations of the Behavior of Energetic Light Ions in Solids