Ionization of low Rydberg He atoms by rotational deexcitation of NH3

Abstract
Ionization of excited helium atoms in nP1(14n16) states due to collisions with the polar molecules NH3 has been studied in a thermal energy crossed-beam experiment. A large ionization signal from these low Rydberg states is observed even though there is insufficient energy available from rotational ΔJ=1, ΔK=0 relaxation transitions of the molecule. In order to explain our observations, large |ΔJ| transitions must be postulated.