Eur. Phys. J. D (2014) 68: 1
https://doi.org/10.1140/epjd/e2013-40528-0

Regular Article

Coulomb heating behavior of fast light diclusters thorough the Si ⟨ 110 ⟩ direction: influence of the mean charge state

Instituto de Física da Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil

^a e-mail: behar@if.ufrgs.br

Received: 26 August 2013
Received in final form: 22 October 2013
Published online: 22 January 2014

Abstract

In this work we report on the results for the Coulomb heating of H⁺₂, B⁺₂ and C⁺₂ diclusters traveling in Si 〈 110 ⟩ direction covering an energy range from 200 keV/ion to 2400 keV/ion. Those results were obtained by combining the Rutherford backscattering spectrometry (RBS) and the particle induced X-ray emission (PIXE) techniques. By comparing the present results to those obtained previously for ions traveling in the narrower Si ⟨ 100 ⟩ channel, several common features are observed for the Coulomb heating values; especially, they follow a linear relationship as a function of the stored potential per ion. However, at variance with previous results, it is shown that the use of a Dirac-Hartree-Fock-Slater (DHFS) potential based on the ion mean charge states in amorphous targets leads to a considerable disagreement between the Coulomb heating values and the expected potential energies stored in the dicluster prior to the Coulomb explosion. In order to investigate this problem, a numerical procedure was developed in order to calculate the mean charge state values for ions traveling under channeling conditions. The use of the resulting charge states led to a linear relationship between the Coulomb heating values and the stored potential energy per ion of the diclusters. Moreover, the Coulomb heating/stored potential energy ratio amounts to about 2/3, which is in full agreement with those results obtained for the Si ⟨ 100 ⟩ direction.