Ionisation energy of $O_2$ to $O^{+}$ O2is very similar to the ionization energy of $Xe$ to $X{e}^{+}$.

The first ionisation energy of $O_2$ to form an $O_2^{+}$ ion as given by the following equation is 1175 KJ/mol. 

$O_2\to O_2^{+}+e^{-}$

This energy is quite close to the ionisation energy of $Xe$ to form $X{e}^{+}$.