Atoms and Molecules as Bound Quantum Systems

Mark R. A. Shegelski, George Jones, Caleb M. Sample +2 more

Abstract This article examines resonant tunnelling of multi-atomic systems, extending the body of work on resonant tunnelling in this area beyond diatomic homo-nuclear systems. We consider diatomic molecules with distinct atoms having different masses, and linear triatomic molecules with indistinguishable atoms. The molecule is incident in the bound state upon a step potential with an energy increase of V 0 for each atom. We calculate the probabilities of reflection p R and transmission p T in the bound state and the dependence on the energy of the molecule. We find that, as was the case for the homo-nuclear molecule, resonant transmission for diatomic molecules with distinguishable atoms occurs for arbitrarily weak binding, and p T is close to one for finite binding energy. We also find resonant transmission for linear triatomic molecules. We show results for the time-dependent Schrödinger equation which agree with resonant transmission. We also consider the transmission of an N -atom one-dimensional molecule.

F. Evangelisti

J. E. Lennard-Jones

Bingcong Gou, Fei Wang

Abstract The bound rotational excited states of weakly bound 4He23He and 3He24He molecules have been searched for. Including pair interaction between helium atoms, we solved the Schrödinger equation for the triatomic systems with hyperspherical coordinates in the adiabatic approximation. The resulting potential curves are mostly repulsive for nonzero angular momenta. We conclude that no bound rotational excited states exist in both 4He23He and 3He24He molecules. The stability of the systems depends sensitively on the quantum symmetry and the masses of the particles. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Walter E Thirring, Evans M. Harrell

T. Schmid, C. Veit, N. Zuber +4 more

We propose a novel experimental method to extend the investigation of ion-atom collisions from the so far studied cold, essentially classical regime to the ultracold, quantum regime. The key aspect of this method is the use of Rydberg molecules to initialize the ultracold ion-atom scattering event. We exemplify the proposed method with the lithium ion-atom system, for which we present simulations of how the initial Rydberg molecule wave function, freed by photoionization, evolves in the presence of the ion-atom scattering potential. We predict bounds for the ion-atom scattering length from ab initio calculations of the interaction potential. We demonstrate that, in the predicted bounds, the scattering length can be experimentally determined from the velocity of the scattered wave packet in the case of ^{6}Li^{+}-^{6}Li and from the molecular ion fraction in the case of ^{7}Li^{+}-^{7}Li. The proposed method to utilize Rydberg molecules for ultracold ion-atom scattering, here particularized for the lithium ion-atom system, is readily applicable to other ion-atom systems as well.