Hyperfine interactions in few-electron fluorine ions recoiling in gases

The nuclear deorientation of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$(5/$2_1^{+}$, 197 keV) has been measured for highly stripped fluorine ions recoiling in He, ${\mathrm{N}}_2$, Ne, Ar, Kr, and Xe at 35 MeV and in ${\mathrm{N}}_2$ and Ar at 55 MeV at gas pressures between ${10}^{-3\mathrm{}}$ and 100 Torr. The nuclear alignment was found to decay quasiexponentially. The extracted nuclear deorientation cross sections are interpreted in a microscopic ion-atom collision model. The dominance of electronic charge-exchange transitions in producing the ionic states of strong hyperfine interactions is demonstrated. Collisional deexcitation of metastable states in heliumlike F is shown to contribute significantly.