Population of the 3s State in Hydrogen Due to H+, H+2 and H+3 Impact on Ethylene, 1-Butene and Cis-2-Butene

Absolute cross sections were measured for capture or dissociation into the 3s state of atomic hydrogen due to impact of 14-28 keV H+, H+2 and H+3 ions on ethylene, 1-butene and cis-2-butene. The cross sections obtained for the butene targets were almost identical and support the additive rule for cross sections. Ethylene cross sections were 21% lower than the values predicted by the additive rule, which agrees well with the observed trend toward reduction in total electron capture cross sections for protons on these gases at much higher energies.