Electronic stopping of Pt for low energy protons and deuterons: velocity dependence and angular distributions

C.E. CELEDON LOPEZ; L. SALAZAR ALARCON; O. GRIZZI, E.A. SANCHEZ, J.E. GAYONE, L. GUILLEMOT, V.A. ESAULOV AND R.A. BARAGIOLA; J. GUIMPEL; P. VARGAS; N.R. ARISTA

Debrecen

Conferencia; 26 International Conference on Atomic Coliisions on Solids; 2014

In recent years, experimental determinations of the energy loss of light ions in metals belonging to Group 11 of the periodic table (Cu, Ag and Au) have shown that,contrary to several theoretical predictions, the stopping power in the low-energy range shows significant deviations for the expected proportionality with ion velocity [1]. These results have been explained by considering the shift in the density of states (DOS) of the d electrons with respect to the Fermi level in those metals [2]. Hence, the deviation from the proportionality of the velocity dependence is related to the particular behavior of d electrons present in transition metals. To gain further knowledge on this phenomenon, we performed additional experiments on the neighboring metals of Group 10 (Ni, Pd and Pt) where the DOS of d electrons reach the Fermi level, and therefore we do not expect a similar deviation from the proportionality in the velocity dependence. This behavior has been experimentally observed in Pd foils and reported in a recent publication [3]. Here we report new measurements of the energy loss of protons and deuterons in thin foils of Pt, showing a significant deviation from the velocity proportionality. These results are in agreement with recent experimental measurements by Bauer et al [4]. We perform also an experimental study of the angular dependence of the energy loss and angular distribution of transmitted particles, and compare these results with theoretical models and computer simulations. The theoretical analysis includes a more detailed study of the local density of states and electronic charge distributions for s, p and d electrons, and provides new hints for the theoretical explanation of the experimental results. [1] J. E. Valdés, G. Martínez Tamayo, G. H. Lantschner, J. C. Eckardt, N. R. Arista, Nucl. Instrum. Methods Phys. Res., Sect. B (1993) 73, 313. [2] J.E. Valdés, J.C. Eckardt, G.H. Lantschner, N.R. Arista, Phys. Rev. A 49, 1083 (1994). [3] C. Celedón, E. A. Sánchez, M. S. Moreno, N. R. Arista, J. D. Uribe, M. Mery, J. E. Valdés, P. Vargas, Phys. Rev. A (2013) 88, 012903. [4] D. Goebl, D. Roth, P. Bauer, Phys. Rev. A (2013) 87, 062903.