A prototype storage ring for neutral molecules

The ability to cool and manipulate atoms with light has yielded atom interf erometry, precision spectroscopy, Bose-Einstein condensates and atom lasers . The extension of controlled manipulation to molecules is expected to be s imilarly rewarding, but molecules are not as amenable to manipulation by li ght owing to a far more complex energy-level spectrum. However, time-varyin g electric and magnetic fields have been successfully used to control the p osition and velocity of ions, suggesting that these schemes can also be use d to manipulate neutral particles having an electric or magnetic dipole mom ent(1-4). Although the forces exerted on neutral species are many orders of magnitude smaller than those exerted on ions, beams of neutral dipolar mol ecules have been successfully slowed down in a series of pulsed electric fi elds(5,6) and subsequently loaded into an electrostatic trap(7). Here we ex tend the scheme to include a prototype electrostatic storage ring made of a hexapole torus with a circumference of 80 cm. After injection, decelerated bunches of deuterated ammonia molecules, each containing about 10(6) molec ules in a single quantum state and with a translational temperature of 10 m K, travel up to six times around the ring. Stochastic cooling(8) might prov ide a means to increase the phase-space density of the stored molecules in the storage ring, and we expect this to open up new opportunities for molec ular spectroscopy and studies of cold molecular collisions(9,10).