Electron-polarised-photon coincidence experiments on the 3¹P state of helium

Abstract

The authors present circular-polarisation measurements of 31P to 21S photons (501.6 nm) detected in delayed coincidence with electrons inelastically scattered upon excitation of the 31P state of helium. They performed these experiments as a function of the electron scattering angle at incident electron energies of 80, 60 and 50 eV in order to study the orbital angular momentum transfer during the collision. The experimental results are compared with previous angular correlation data and with theory. For each incident electron energy they found a sign reversal of the angular momentum transfer as a function of the electron scattering angle.