Oxygen Emissions from Single-Crystalline Fe$\text{}_{3}$O$\text{}_{4}$ Surfaces Induced by Low-Energy Ion Bombardments

Negative-charged ion energy spectra of the Fe$\text{}_{3}$O$\text{}_{4}$ (001) and (111) surface revealed large peaks attributed to the O$\text{}^{-}$ recoils from a binary collision. Under Ar$\text{}^{+}$ ion bombardments such an emission was largely affected by the screening effect of the Fe ions. A distinguished peak related to the O$\text{}^{+}$ recoil ions was observed under Ne$\text{}^{+}$ ion bombardments, while such a peak was merged into the high background in the case of Ar$\text{}^{+}$ ion ones. A weak effect from the Verwey transition was found on oxygen emissions. For the (111) surface a small peak characteristic of the O$\text{}^{+}$ recoils from double collisions appeared in the energy spectra around 140-170 K and a minimum was observed in both R$\text{}^{+}$(T) and R$\text{}^{-}$(T) curves under 6 keV Ne$\text{}^{+}$ ion beam.