Magneto-Optical Trap for Sodium Atoms from a Vapor Cell and Observation of Spatial Modes

During the pa;t few years there has been an enormous progress in the use of light to manipulate the translational degr:es of freedom of atoms. Laser light resonant with an atornic transition has been used to slowl, coo12 and ti.ap3 neutral atorns. An intense effort is now being carritsd out with the purpose of using laser radiation techniques t o improve methods of atomic manipulation in order to produce intense beams of slow atorns or dense tr#ips where slow energy collisions and ultra-high precisicn spectroscopy will find interesting applications. If s~fficiently high density and low temperature are attaired, one may expect to observe collective effects, such as Bose-Einstein Condensation4. Until recently, the production of cold trapped atoms was achieved in a two-step process, when it was demonstrated that cesiun atoms in the low velocity tail of a thermal distribu ;ion can be directly captured from a vapor5. In spite of technical difficulties arising from different operational conditions, sodium atoms may also be confined in a sinilar way. Trapped cold atorns may present intriguing spatial configurations, depending on the position and transverse intensity profile of the laser beams used. One of the possible spatial distributions of cold trapped atomic samples is a ring which recently has been associated with collective efferts in trapped neutral atoms. However, experiments ivith sodiuma revealed that, depending on the laser configuration and profile, it is possible to obtain stable r ngs of trapped atoms without the need of the existence of a collective behavior t o explain the results. Another interesting configuration of magneto-optically t rapped atoms is a double stable trap which has been observed since the first demonstration of Magneto-Optical trapping but, to our knowledge, was never explained. In this paper wt, discuss the achievement of trapped sodium atoms in a vapor cell and the observation of spatial atomic distributions which are justified on the basis of the radiation pressure.