Energy dependence of cross sections for double-electron capture in 48–132-keVC6++He collisions

Abstract

We report on the projectile energy dependence of the cross sections for producing the configurations 2${\mathit{lnl}}^{\prime }$ (n≥3) by double-electron capture in ${\mathrm{C}}^{6+}$+He collisions. The present measurements and calculations, which extend previous work performed on the 90-keV ${\mathrm{C}}^{6+}$+He system, give evidence for dynamic electron-correlation effects in double-capture mechanisms. A significant dependence on the collision energy is found for the cross sections associated with the configurations 2${\mathit{lnl}}^{\prime }$ (n≥5). Moreover, anisotropies of the angular distributions of Auger electrons originating from the configurations 2l3${\mathit{l}}^{\prime }$ are observed at 48 and 132 keV. The capture cross sections for producing some of the terms 2l3${\mathit{l}}^{\prime }$ ${}_{}{}^1{}_{}{}^{}$L are shown to depend on the collision energy. The cross sections for production of the magnetic substates ${\mathit{M}}_{\mathit{L}}$=0 associated with the configurations 2l3${\mathit{l}}^{\prime }$ are found to be the same for both energies of 48 and 132 keV. © 1996 The American Physical Society.