Studies of threshold behavior in electron-molecule collisions using ultra-high-n Rydberg atoms
Frey, Mark T.
Dunning, F. B.
Master of Science
Potassium atoms in selected high-lying Rydberg states (n $<$ 1200) are used as a tool to probe threshold behavior in electron-molecule collisions. Collisions with non-polar electron attaching molecules such as CCl$\sb4$ are dominated by electron capture in a binary interaction between the Rydberg electron and target molecule allowing the study of electron attachment at electron energies of only a few $\mu$eV. Analysis of the data shows the cross section for electron capture is consistent with the Wigner threshold law for an inelastic s-wave process. Collisions with polar molecules can lead to Rydberg atom destruction through transfer of molecular rotational energy to the Rydberg electron. Rydberg atom data obtained with polar targets are not consistent with scattering from a static dipole. However, the data are consistent with a threshold law that takes into account a rotationally-averaged induced dipole interaction that can possibly support bound or virtual states.
Atomic physics; Molecular physics