Photodetachment Cross Sections for He-(4P°)

We report the first measurements of photodetachment cross sections for He- (formed through charge exchange of He+ with Ca vapor) over the photon energy range from 1.77 to 2.75 eV. The energies of auto-detached electrons from the metastable He beam have also been determined for the first time. The autodetached electron energy agrees within experimental error (±0.25 eV) with the known 1s2s2p)4P° He- energy level. This taken with measurements for the lifetime of He- infers that change exchange of He+ with Ca vapor produces 4P° He-.