${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ atomic polarizations following the spin-polarized electron capture process for the Na→(3s)${+}^3$${\mathrm{He}}^{2+}$ system were measured at ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{2+}{}_{}{}^{}$ impact energies from 5.33 to 9.33 keV/amu. The magnitude of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ atomic polarizations was deduced from the ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ nuclear polarization measured by means of beam-foil spectroscopy. The observed polarization transfer coefficient ${\mathit{P}}_{\mathit{T}}$ defined by the ratio of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ atomic polarization to the sodium one showed a pronounced reduction from unity, which was qualitatively explained by the prediction of a simple cascade photon decay model. Evidence for a further reduction of ${\mathit{P}}_{\mathit{T}}$ from the above model and a possible impact energy dependence of ${\mathit{P}}_{\mathit{T}}$ suggested an excessive depolarization due to the presence of the collision alignment parameter ${\mathit{A}}_0^{\mathrm{col}}$ of ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ formed by the electron capture process. In order to see this more closely, the observed ${\mathit{P}}_{\mathit{T}}$’s were examined theoretically using the semiclassical impact parameter method, in which an 18-state molecular expansion was employed, and atomic-type electron translation effects were rigorously taken into account. Ensuring that both the absolute values and the impact energy dependence of the observed capture cross sections were remarkably well reproduced by the calculations in which the states up to 4f in ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ were introduced, it was demonstrated that the calculated results for ${\mathit{P}}_{\mathit{T}}$ qualitatively reproduced not only the absolute values of the observed ${\mathit{P}}_{\mathit{T}}$’s but also their gentle decrease with increasing impact energy. Production of nuclear polarizations resulting from the polarized electron capture processes between multicharged heavy ions and alkaline-earth-metal atoms is offered as one of the promising applications to the future project of universal polarized heavy-ion sources.

• Received 5 January 1994

DOI:https://doi.org/10.1103/PhysRevA.50.1184