The influence of the mean charge state on the Coulomb heating of fast diclusters through the Si〿 1 1〿direction

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• 作者：C.D. Nascimento ; R.C. Fadanelli ; ^{raul@if.ufrgs.br" class="auth_mail" title="E-mail the corresponding author} ; M. Behar
• 关键词：Coulomb heating ; Diclusters ; Charge state
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：1 April 2016
• 年：2016
• 卷：372
• 期：Complete
• 页码：86-90
• 全文大小：960 K

文摘

In the present work, we report a theoretical and experimental study of the Coulomb heating of age" height="20" width="22" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0168583X16001312-si1.gif">${\text{H}}_2^{+}$ and age" height="20" width="20" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0168583X16001312-si2.gif">${\text{C}}_2^{+}$ in Si〈1 1 1〉 channel, covering an energy range from 200 keV/ion to 2200 keV/ion. The experimental values for Coulomb heating were obtained by combining the Rutherford backscattering spectrometry (RBS) and the particle induced X-ray emission (PIXE) techniques under channeling conditions. Theoretical values were obtained by performing classical trajectory Monte-Carlo (CTMC) simulations of the ion paths inside the 〈1 1 1〉 Si channel, using Dirac–Hartree–Fock–Slater (DHFS) results for the interionic potential. As seen for the 〈1 1 0〉 case, it is shown that the use of a DHFS potential based on the ion mean charge states in amorphous targets leads to a disagreement between the Coulomb heating values and the expected potential energies stored in the dicluster prior to the Coulomb explosion. Therefore, a numerical procedure was used in order to calculate the mean charge state values for ions traveling in Si〈1 1 1〉. 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. Finally, the Coulomb heating/stored potential energy ratio amounts to about 2/3, as expected from an isotropic Coulomb explosion.