Universität zu Köln

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:	Creators Email ORCID ORCID Put Code Grussie, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Berg, M. H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Crabtree, K. N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gaertner, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED McCall, B. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlemmer, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wolf, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kreckel, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED
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:	Keywords Language INTERSTELLAR MOLECULAR-HYDROGEN; 22-POLE ION-TRAP; SELECTION-RULES; CLOUDS; SPECTROSCOPY Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/47968