Atoms In High Rydberg States Research Articles

Ionization of xenon atoms in high Rydberg states by collision with molecules

Ionization of xenon atoms in single highly excited states ‖nf≳ (where 25⩽n⩽40) by collisions with CCl4, CCl3F, and SF6 has been investigated. Absolute rate constants for Xe+ production are reported together with the identities of the major negatively charged species produced in the collisions. Cross sections determined from these rate constants are also given. The data lend support to the theoretical model, which views such collisions as being dominated by the interaction between the target molecules and the excited electron, with the Xe+ ion core playing a minor role.

Dissociative recombination of the hydrogen molecular ion

Recent experiments on the dissociative recombination of H2+ and D2+ are summarized and the projection operator formalism of resonance scattering processes in molecules is reviewed. The application of the theory to specific systems requires the calculation of electronic energies and matrix elements, and of vibrational wavefunctions; comprehensive results are presented for H2+ and D2+. To obtain further insight the author develops a semiclassical theory which is surprisingly successful; in particular the cross sections for producing atoms in high Rydberg states are predicted to be large, in agreement with experiment. The rate of recombination at thermal energies (<300K) requires special consideration: it is shown that the so-called indirect mechanism is significant and that the total thermal rate is reasonably fast.

Highly excited atoms excite interest in many labs

“Since I'm an atom as big as bacterias I've got to take microwaves serious. No matter what I do, I'll be cryin'… After they hit me, I'll be an ion.” So begins a poem written last year by Peter Koch of Yale, during the stresses of preparing his PhD thesis. With James Bayfield, Koch had been studying highly excited atoms (often called “atoms in high Rydberg states,” or even simply “Rydberg atoms”); the interesting behavior of such atoms has become the subject of current experimental and theoretical work at many centers around the world.

Studies of xenon atoms in high Rydberg states

Thermal beams of xenon atoms in single high Rydberg states have been produced by photoexcitation of $\mathrm{Xe}(^{3}P_{0})$ metastable atoms. The highly excited states which were populated in this way were identified as $\mathrm{np}{[\frac{1}{2}]}_{1}$ with $11\ensuremath{\le}n\ensuremath{\le}16$ and $\mathrm{nf}{[\frac{3}{2}]}_{1}$ with $8\ensuremath{\le}n\ensuremath{\le}40$. The field ionization characteristics and radiative lifetimes of these atoms have been studied.