Shape resonance observed in fast collisions of Li(sup (minus)) ions with gas targets

摘要

A shape resonance state in the Li(sup (minus)) ion. identified as the 2s2p (sup 3)P(sup o) state. has been populated in 100 keV collisions with a He gas target. The resonance was observed via zero-degree electron detachment spectroscopy in which kinematic shifting and doubling were exploited in the detection of the very low energy electrons. The electrons ejected via the resonance gave rise to structures in the electron energy spectra that were disposed about a continuum cusp. These structures corresponded to forward- and backward-directed emission in the projectile frame. Laser photodetached electron spectroscopy was used to accurately calibrate the electron energy scale and to determine the spectrometer resolution function. Preliminary analysis indicates that the measured position and width of the resonant state agree with theoretical values.