Studies of Highly Polar Atomic and Molecular Systems: Quantum Dynamics and the Route to Experimental Investigations

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Date
2009-12-09T22:15:56Z
Authors
Collister, Robert A.
Keyword
Atomic Physics , Molecular Physics , Adiabatic Quantum Mechanics , lithium , Stark Effect , Rydberg states/systems , Ion-pair Formation , Colliding Atoms
Abstract
Theoretical investigation of the dynamics of adiabatic quantum mechanics in two different, highly polar systems has been made. The systems were chosen for their fundamental scientific interest, as they represent atoms and molecules with exaggerated properties, as well as ease of experimental study as such highly polar systems are easier to manipulate using readily-available electric fields. A model two-level system is used to derive one approach for maximizing the probability of adiabatic passage through an avoided crossing and this is compared with the classic Landau-Zener result, and the commonly encountered spin-flip problem of a particle with spin located in a rotating magnetic field. This approach is applied to the avoided crossing between the n = 13, n1 − n2 = 11 (dipole moment of 532 D) and the n = 14, n1 − n2 = −12 (dipole moment of -657 D) highly polar Stark states of the lithium atom at 447 kV/m. Ion-pair formation from two neutral lithium atoms, one in the 2s ground state and the other in an excited state, is also investigated. The cross section σ(v) for free ion-pairs is calculated for the initial colliding pairs of atomic states located below the ion-pair threshold. Li(2s) + Li(3d) is seen to possess the largest cross section (σ(v0) = 569.2 a.u.) at its threshold velocity. The implications of this for bound ion-pair, i.e. heavy Rydberg system, production are briefly discussed. Furthermore, experimental progress towards the production of these atomic and molecular systems from a beam of lithium is presented.
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