High-resolution dissociative recombination of cold H3+and first evidence for nuclear spin effects.
The energy-resolved rate coefficient for the dissociative recombination (DR) of H(3)(+) with slow electrons has been measured by the storage-ring method using an ion beam produced from a radiofrequency multipole ion trap, employing buffer-gas cooling at 13 K. The electron energy spread of the merged-beams measurement is reduced to 500 microeV by using a cryogenic GaAs photocathode. This and a previous cold- measurement jointly confirm the capability of ion storage rings, with suitable ion sources, to store and investigate H(3)(+) in the two lowest, (J,G) = (1,1) and (1,0) rotational states prevailing also in cold interstellar matter. The use of para-H(2) in the ion source, expected to enhance para-H(3)(+) in the stored ion beam, is found to increase the DR rate coefficient at meV electron energies.
Max-Planck-Institut für Kernphysik, Heidelberg, Germany.
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Kreckel
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Motsch
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Mikosch
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Glosík
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Plasil
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Altevogt
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Andrianarijaona
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Buhr
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Hoffmann
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Lammich
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Lestinsky
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Nevo
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Novotny
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Orlov
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Pedersen
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Sprenger
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Terekhov
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Toker
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Wester
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Gerlich
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Schwalm
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Wolf
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Zajfman