Collision spectroscopy with aligned and oriented atoms. Pt. 4

Neutralisation processes in 0.15-1.5 keV collisions of H- with Na atoms in the 3s ground state or in the excited 3p state have been investigated by means of time-of-flight analysis of the neutral H atoms produced. The H--Na(3p) system, investigated here for the first time, is particularly interesting since the entrance channel is embedded in the [H-Na(3s)]+e- continuum, enabling Penning detachment to occur. The measured relative neutralisation cross section ratios σ(3p)/σ(3s) decrease from 3 to 1.6 with increasing energy. Based on earlier published results for σ(3s), σ(3p) total cross sections exceeding 100 A2 are estimated. (orig.)