Differential Measurement of the He3P3Excitation, inHe+-He Collisions, by Using an Ion-Photon Coincidence Method

Abstract

In order to determine the differential cross section for excitation of a given radiative level, in ion-atom collisions, the scattered ions are detected at a given angle, in coincidence with the photons emitted by the excited target atoms. The method has been applied to the ${\mathrm{He}}^{+}$-He collision at laboratory energies of 200, 300, and 350 eV in the angular range 5-18 deg, for the $3{}_{}{}^3{}_{}{}^{}P$ level of He. At 200 and 300 eV, the differential cross sections exhibit an interference pattern which is characteristic of a curve crossing. The behavior is more complicated at 350 eV because, we believe, more than two molecular states are involved.