ELECTRON-IMPACT DETACHMENT FROM NEGATIVE-IONS

Electron-impact detachment cross sections have been measured from thre shold to about 30 eV for D- and O-. The purpose was to investigate the cross section near threshold and to reinvestigate earlier claims of r esonances due to short-lived states of the doubly charged negative ion . Initial results for D- showed no resonances [L. H. Andersen, D. Math ur, H. T. Schmidt, and L. Vejby-Christensen, Phys. Rev. Lett. 74, 892 (1995)]. Here we show that there is no detectable resonance structure for O- either. The applied experimental technique is discussed in deta il. Classical and semiclassical models for the detachment process are presented and compared with the data.