Grussie, F., Berg, M. H., Crabtree, K. N., Gaertner, S., McCall, B. J., Schlemmer, S., Wolf, A. and Kreckel, H. (2012). THE LOW-TEMPERATURE NUCLEAR SPIN EQUILIBRIUM OF H-3(+) IN COLLISIONS WITH H-2. Astrophys. J., 759 (1). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

Recent observations of H-2 and H-3(+) in diffuse interstellar sightlines revealed a difference in the nuclear spin excitation temperatures of the two species. This discrepancy comes as a surprise, as H-3(+) and H-2 should undergo frequent thermalizing collisions in molecular clouds. Non-thermal behavior of the fundamental H-3(+)/H-2 collision system at low temperatures was considered as a possible cause for the observed irregular populations. Here, we present measurements of the steady-state ortho/para ratio of H-3(+) in collisions with H-2 molecules in a temperature-variable radiofrequency ion trap between 45 and 100 K. The experimental results are close to the expected thermal outcome and they agree very well with a previous micro-canonical model. We briefly discuss the implications of the experimental results for the chemistry of the diffuse interstellar medium.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Grussie, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Berg, M. H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Crabtree, K. N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gaertner, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
McCall, B. J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schlemmer, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wolf, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kreckel, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-479680
DOI: 10.1088/0004-637X/759/1/21
Journal or Publication Title: Astrophys. J.
Volume: 759
Number: 1
Date: 2012
Publisher: IOP PUBLISHING LTD
Place of Publication: BRISTOL
ISSN: 1538-4357
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
INTERSTELLAR MOLECULAR-HYDROGEN; 22-POLE ION-TRAP; SELECTION-RULES; CLOUDS; SPECTROSCOPYMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/47968

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