Kurzlebige Compoundzustände in der niederenergetischen Elektron-Helium-Streuung

Abstract

Electron scattering measurements have been made of the energy dependences of the excitation of the Helium 2³ S, 2¹ S, 2³ p, and 2¹ P states at different scattering angles in the range from 20 to 145°. In the energy range from 22 to 23 eV five overlapping resonances of the (e-He)-system have been determined, one of which (22.42 eV) is identified to be a 3² S, another (22.60 eV) a 3² P-state. The energy values of the other resonances are resp. 22.55, 22.75, and 22.85 eV. The half-widths are below approximately 40 meV. In the 2³ P-channel three peaks vanish at the same scattering angle, a fact, which seems not understandable in terms of first order resonance poles.