VIBRATIONAL COOLING OF D-2(-RING AS REVEALED BY DISSOCIATIVE RECOMBINATION MEASUREMENTS() IN AN ION STORAGE)

It is demonstrated that a substantial degree of vibrational cooling of an infrared inactive molecule can be achieved by means of storage in an ion cooler ring. The cross section for dissociative recombination o f D2+ has been measured in the storage ring CRYRING using 6 MeV amu-1 ions and variable storage times prior to data taking. By using a simpl e model for describing the recombination process, it is inferred that 68% of the D2+ ions remaining in the ring after 22.5 s populate nu = 0 . It is proposed that the removal of vibrational excitation contained in the ions injected into the ring is due to collisions in the rest ga s. The rate coefficient measured for 22.5 s storage time, alpha(T = 30 0 K) = 2.3 x 10(-8) cm3 s-1, is in very good agreement with theoretica l predictions.