Theoretical and experimental study of energy loss of Li ions in Zn

Abstract

We have performed a combined theoretical and experimental study of the energy loss of Li ions in Zn, on a wide range of energies, together with comparative studies for H and He ions on the same target. By using Zn films and the Rutherford backscattering technique, we were able to determine the stopping power for Li ions in the ͑0.3 to 5͒ MeV energy interval. The experimental results cover an energy range which includes the maximum of the stopping power. The values obtained agree well with previous measurements performed in a limited energy interval and with the semiempirical code SRIM 2006. On the other hand, we have performed ab initio theoretical calculations based on the extended Friedel sum rule-transport cross section formulation for the valence electrons and the shellwise local plasma approximation for the inner shells. This theoretical description reproduces reasonably well the experimental results on the whole studied energy range. The same occurs with previous measurements performed with H and He on the same target. The importance of the screened potential on the stopping power due to the valence electrons is stressed in the present description.

Experimental and theoretical study of the energy loss of C and O in Zn

“…It is worthwhile to mention that for ions heavier than Li, the experimental stopping power data are scarce except for some particular materials (C, Al, Si, Ag, Au) [3]. In zinc, no energy loss measurements for C and O ions have been reported in the literature.In previous papers, we have studied in a systematic way the stopping coefficients for a series of ions of increasing atomic numbers: H, He, Li, Be, and B in zinc [4][5][6][7][8], and with our theoretical formulation, we have been able to explain changes in the stopping power curves, reaching a very good agreement between the experimental and theoretical results. This agreement was achieved by a detailed theoretical study of the contribution of each individual charge state of the projectile and each electronic shell of the target.…”

“…The targets were made of a multilayered Au-Zn-Au film deposited on Si wafers, as in previous works [7,8]. Several target thicknesses were used according to the different energies and projectiles used in the present experiment.…”

“…The theoretical approaches used to calculate the energy loss of ions in solids have been described in detail in previous publications [6][7][8].…”

“…[17]. The stopping power due to valence electrons was calculated considering them as a free electron gas (FEG) using the TCS-EFSR approach [9], as described in previous papers [6][7][8]. The TCS-EFSR is a nonlinear or nonperturbative model, since it contains no linearizing or perturbative assumptions, and, therefore, it applies to all orders in the interaction.…”

Progress in understanding heavy-ion stopping

“…The difference between experimental and CasP data is greater than for O-Al, and also PASS data deviate noticeably from measurements, in particular in the velocity range below v 0 . Figure 5 shows comparisons between PASS and SLPA [23,27] data and measured stopping cross sections in Zn. With the exception of He-Zn, where experimental data scatter substantially at the low-energy end, differences between PASS and SLPA as well as between experiment and the two theoretical schemes are below 20%.…”