He(3P3)excitation in 1.5- and 3.0-keVHe++H2collisions

Photon-scattered-atom coincidence measurements, for the collision ${\mathrm{He}}^{+}+{\mathrm{H}}_2\to \mathrm{He}\left(3\mathrm{}{}_{}{}^3{}_{}{}^{}P\right)+{{\mathrm{H}}_2}^{+}$, both with and without linear polarization analysis, have been made for small-angle scattering of He at 1.5 and 3.0 keV. A very large polarization for the $3{}_{}{}^3{}_{}{}^{}P$ to $2{}_{}{}^3{}_{}{}^{}S$ transition is observed at 1.5 keV, 1.5° and 3.0 keV, 1.25°. Also, the excitation probability exhibits small but definite structure as a function of scattering angle.