Slowing and cooling molecules and neutral atoms by time-varying electric-field gradients

Abstract

A method of slowing, accelerating, cooling, and bunching molecules and neutral atoms using time-varying electric field gradients is demonstrated with cesium atoms in a fountain. The effects are measured and found to be in agreement with calculation. Time-varying electric field gradient slowing and cooling is applicable to atoms that have large dipole polarizabilities, including atoms that are not amenable to laser slowing and cooling, to Rydberg atoms, and to molecules, especially polar molecules with large electric dipole moments. The possible applications of this method include slowing and cooling thermal beams of atoms and molecules, launching cold atoms from a trap into a fountain, and measuring atomic dipole polarizabilities.

Ro-vibrational quenching of CO (v = 1) by He impact in a broad range of temperatures: A benchmark study using mixed quantum/classical inelastic scattering theory

“…Thus, experimental studies of inelastic transitions in CO + He is an important benchmark, which has many potential applications including the high resolution molecular spectroscopy and controlled chemical reactions. 26,27 Also, the study of vibrational relaxation of CO by collisions with He atoms provides a convenient general model which could be used for analysis of relaxation processes involving other diatomic molecules and other lowmass collision partners. 13 In the past, significant efforts have been devoted to testing and refining the potential energy surface (PES) for interaction between CO and He.…”

Hot Prospects for Ultracold Molecules

“…More recently, researchers from the Lawrence Berkeley National Laboratory and the University of California, Berkeley, have applied a similar technique to slow neutral atoms. 3 Bretislav Friedrich of Harvard points out that electric fields, unlike their magnetic counterparts, can be switched quickly on the time scale of molecular translation. The corresponding dynamics of electrical trapping exhibit different and, at this point, novel phenomena.…”

“…At that point, the electric field was changed to a symmetric configuration with a minimum at the center. By ionizing and detecting a small volume of the trapped molecules, the Dutch experimenters have determined the density to be 10 6 /cm 3 , and they estimate their volume to be about 0.25 cm 3 . So far the team does not have a direct measurement of the temperature of the trap, but team members suspect it is appreciably less than the depth of the trap's potential well, or 350 mK, corresponding to a few tens of meters per second.…”

“…In this work, the Dutch group cooled and trapped molecules in a single quantum level with a density of 10 6 /cm 3 and at temperatures estimated to be well below 350 mK. 1 With trapped molecules, one would ideally like to achieve three things: reduce translational temperatures to submillikelvin levels; cool a large number of molecules; and put the molecules in a single, and preferably the lowest, rotational-vibrational state.…”

Improved alternating gradient transport and focusing of neutral molecules

“…For laboratory electric fields this interaction is much smaller than the interaction with a molecular electric dipole moment, but it can be used to focus atoms [8] or decelerate them [15].…”