Eur. Phys. J. D 26, 27-32 (2003)
https://doi.org/10.1140/epjd/e2003-00200-0

Effects of electric fields and collisions on highly excited rubidium atoms

Departments of Chemistry and Physics, The University of Tennessee, Knoxville TN 37996, USA

Corresponding author: ^a rcompton@utk.edu

Received: 12 November 2002
Revised: 11 March 2003
Published online: 8 July 2003

Abstract

The effects of static and pulsed electric fields on the multiphoton ionization (MPI) of rubidium atoms at both low (atomic beam) and high (heat pipe) densities are studied using tunable OPO lasers. Two-photon excitation of np states is induced by the external electric field at both low and high densities. In addition, np signal is also seen at very low electric fields in the heat pipe, providing evidence for collision mixing as well as field mixing. At low Rb densities strong resonance features are observed in the energy region between the zero field limit (IP) and the field ionization limit. In addition, collisional detachment and charge transfer between excited ns and nd Rb Rydberg states and nozzle-jet cooled polar molecules (acetonitrile and acetone) are studied under crossed-beam conditions. The formation of dipole bound anions for acetone is only seen under nozzle jet expansion conditions and the maximum in the Rydberg electron transfer (RET) rate versus n depends upon the expansion gas (n_max increases in the order H₂, He, Ne, Ar, Xe). For acetone (low dipole moment and large n_max), collisional detachment dominates the charge transfer, whereas for acetonitrile (high dipole moment and low n_max), charge transfer is seen to dominate the creation of Rb⁺.