Elastic scattering of metastable helium from helium, a molecular beam study of the helium excimer potentials

The long range parts of the A 1Σ+sub(u) and C 1Σ+sub(g) helium excimer potentials have been studied in a crossed atomic beam experiment. The experimental details have been described earlier in detail. Helium atoms of a supersonic beam of variable kinetic energy (16 - 250 meV) and very good velocity resolution (1 to 8 %) is excited by coaxial electron impact to the two metastable states (1s2s, 21S and 23S). The singlet state can be quenched optically. This beam is crossed at a right angle with a beam of ground state He atoms, and the angular distribution of the excited helium (He*) atoms is measured. (Auth.)