Simultaneous excitation of both collision partners in He-He collisions

Abstract

The energy dependence of the cross section for simultaneous excitation of both collision partners to the 33D state in He-He collisions has been measured at incident energies between 0.9 and 3.5 keV. At an incident energy of 1750 eV this cross section reaches a maximum of about 5.5% of the cross section for excitation of one atom to the 33D state, whatever the final state of the other atom. Further, at 1500 eV ratios have been measured of the cross sections for simultaneous excitation of one atom to the 33D state and the other to different n>or=3 triplet states. From these measurements it can be concluded that the 33D state is only for about 7% simultaneously excited with n>or=3 triplet states, which means that in simultaneous excitation with one atom in the 33D state there is a more than 90% probability to find the other atom in the 23S or 23P state.