Near--K-edge double and triple detachment of the F- negative ion: observation of direct two-electron ejection by a single photon.

Double and triple detachment of the F-(1s2 2s2 2p6) negative ion by a single photon have been investigated in the photon energy range 660 to 1000 eV. The experimental data provide unambiguous evidence for the dominant role of direct photo-double-detachment with a subsequent single-Auger process in the reaction channel leading to F2+ product ions. Absolute cross sections were determined for the direct removal of a (1s+2p) pair of electrons from F- by the absorption of a single photon.