  A promising method to investigate dark exciton transitions in quantum dots is
presented. The optical recombination of the dark exciton is allowed when the
exciton state is coupled with an individual magnetic impurity (manganese ion).
It is shown that the efficient radiative recombination is possible when the
exchange interaction with the magnetic ion is accompanied by a mixing of the
heavy-light hole states related to an in-plane anisotropy of the quantum dot.
It is also shown that the dark exciton recombination is an efficient channel of
manganese spin orientation.
