We investigated l and m-distributions of He II (n = 4) states formed during 2-13.3 keV amu(-1) He2+ + Na(3s) collisions by measuring profiles and the linear polarization of the He II (4 --> 3) emission. We found that at these energies capture into He+(4f) dominates over capture into other He+(4l) states. Over the indicated energy range the polarization of the He-4 II (4 --> 3) photon emission increases from 0.2 to 0.3 indicating a strong alignment of the captured projectile charge cloud along the internuclear axis. Due to the non-zero nuclear spin the polarization is up to 10% lower when using He-3(2+) projectiles instead of He-4(2+). Classical trajectory Monte Carlo calculations agree quantitatively with these experimental findings and predict a decrease of the polarization towards zero at higher energies due to enhanced capture into He+(4s).
A positive polarization is also found for the Na I (3p --> 3s) target de-excitation. However, due to strong depolarization effects caused by the nuclear spin of the Na-23 nucleus it stays below 0.14.
|Tijdschrift||Journal of Physics B-Atomic Molecular and Optical Physics|
|Nummer van het tijdschrift||15|
|Status||Published - 14-aug-1995|