“…For photon energy regimes where inner-shell detachments is possible, e.g., studies of He − [14], Li − [12,13], C − [15], and S − [22], the double detachment reaction mostly seems to proceed as a sequential process of inner-shell electron detachment followed by Auger decay showing, however, also delicate processes near thresholds such as the postcollisional re-capture [19,24] and the double Auger decay from a hollow resonance [18]. In contrast, for photon energy regions where valence electrons are accessed, e.g., experiments on Na − [11], F − [16], and Cl − [17], double detachment mechanisms both of indirect (sequential) nature, involving detachment into excited neutrals states followed by autoionization, and of direct nature with simultaneous emission of two electrons have been discussed. In particular, for the halogen anions F − [16] and Cl − [17] simultaneous processes are believed to dominate over sequential processes.…”