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Abstract

Ion storage and trapping techniques in connection with efficient internal state control and diagnostic for molecular ions offer the potential of providing rate coefficients for the dissociative recombination of H₃⁺ for well-defined initial rotational states, required for understanding the role of this ion in the interstellar medium and other cold environments. Information on the vibrational and rotational excitation in stored H3+ ion beams, as obtained from experiments at the ion storage ring TSR, is reviewed. In addition, the arrangement of the TSR injector trap, using buffer gas cooling in a cryogenic radiofrequency multipole structure to inject pulses of internally cold H3+ ions into the TSR via a high-energy accelerator, is outlined. An account is given of tests towards the in-situ diagnostic of rotational level populations, where laser transitions between low-lying rovibrational levels could be detected in dilute H₃⁺ ion ensembles using chemical probing in the radiofrequency multipole ion trap.