Polarized photon emission following He +He charge capture collisions

Abstract

The polarization of 3889 Å photons from the 2 3S3 3P transition of fast helium atoms produced by charge capture in a He +He collision has been measured as a function of the reduced angle τ= Eθ. An impact parameter selection method was employed with ions having energies between 2 and 3 keV, and at scattering angles of a few degrees. Circular polarizations, and in some cases linear polarization, of the light was measured. Large circular polarization, corresponding to collisional orientation, were observed. The results are discussed with reference to other measurements, and to the electron promotion model.