Controlling translational motion of neutral molecules in inhomogeneous electric fields

H. D. Lambropoulos

David Townsend, Simon R. Procter, A L Goodgame +1 more

A L Goodgame, T. P. Softley

A novel theoretical study of the control of translational motion of atomic and molecular Rydberg states in inhomogeneous static electric fields is presented. Simulations have been carried out demonstrating that, under realistic conditions, the deflection and focusing of Rydberg atoms and molecules should be achievable. Advantage is taken of the high susceptibility of the Rydberg states to external electric fields, allowing the use of much smaller fields than would be necessary for ground state neutrals. The simulations presented are for trajectories of Rydberg states with n = 18-20 in the fields of an electric dipole, quadrupole and hexapole. A deflection of 7 mm is predicted for n = 18 Rydberg states travelling parallel to the dipole after 100 µs time of flight. In the hexapole n = 20 Rydberg states are refocused to a spot size of the order of the laser beam waist (10 µm) after 20 µs. It is demonstrated that the hexapole can also act as a cylindrical lens if its axis is perpendicular to the Rydberg beam direction. Spontaneous emission and black-body decay rates are also calculated, and their variation with the applied field is investigated. The potential applications of this work might include the use of focusing and deflection for controlled low-energy collisions of Rydberg molecules with surfaces.

Hendrick L. Bethlem, Giel Berden, André J. A. van Roij +2 more

A series of pulsed electric fields can be arranged such that it creates a traveling potential well in which neutral dipolar molecules can be confined. This provides a method to transport, to decelerate, and to cool a sample of neutral molecules while maintaining the initial phase-space density. This method is described using the concept of phase stability. The oscillating motion of molecules in the traveling potential well, reaching a minimum velocity spread corresponding to a translational temperature of 4 mK, is experimentally observed.

Elizabeth Todd Davies

The ability to deflect neutral polar molecules present in supersonic molecular beams using inhomogeneous electric fields is a consequence of these molecules possessing a dipole moment. As a dipole moment is inherently a quantum state-dependent feature, it can thus be exploited to allow spatial separation of neutral molecules in different quantum states. In this report, the Stark interaction was exploited to provide deflection of a gaseous sample of indole (C8H7N). Spatial profiles of the molecular beam at various electric field strengths were measured, showing an observed deviation in the beam path attributed to the indole molecules residing in different quantum states. These state-selected samples produced act as ideal samples for laser alignment techniques, in preparation for further experiments such as diffraction on gaseous molecular samples.

Simon R. Procter, Yoshihiro Yamakita, Frédéric Merkt +1 more