Reactions of metastable atoms and resonance photons

Collision experiments with He 2 3S and Ne 3P metastable atoms are described, giving the total collision cross-sections of these atoms and their resonance photons with He, Ne, A at thermal energies. Their values are discussed in terms of energy considerations. The secondary electron yields from He metastable atoms incident upon W, Mo, Pt surface flashed to 1700 °C are compared with the yield from an unflashed Au surface, which is known absolutely from the experiments of Stebbings. The gas contamination of the surface causes the yields to rise. The absolute yields from atomically clean surfaces are calculated and compared with the data of Hagstrum for positive ions. The yields for the resonance photons have also been determined, and are compared with the data of various workers.