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

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.