Volume 581, September 2015
|Number of page(s)||7|
|Section||Interstellar and circumstellar matter|
|Published online||11 September 2015|
H2 formation via the UV photo-processing of a-C:H nano-particles
Université Paris Sud and CNRS, Institut d’Astrophysique Spatiale, UMR
Received: 7 May 2015
Accepted: 26 July 2015
Context. The photolysis of hydrogenated amorphous carbon, a-C(:H), dust by UV photon-irradiation in the laboratory leads to the release of H2 as well as other molecules and radicals. This same process is also likely to be important in the interstellar medium.
Aims. We investigate molecule formation arising from the photo-dissociatively-driven, regenerative processing of a-C(:H) dust.
Methods. We explore the mechanism of a-C(:H) grain photolysis leading to the formation of H2 and other molecules/radicals.
Results. The rate constant for the photon-driven formation of H2 from a-C(:H) grains is estimated to be 2 × 10-17 cm3 s-1. In intense radiation fields photon-driven grain decomposition will lead to fragmentation into daughter species rather than H2 formation.
Conclusions. The cyclic re-structuring of arophatic a-C(:H) nano-particles appears to be a viable route to formation of H2 for low to moderate radiation field intensities (1 ≲ G0 ≲ 102), even when the dust is warm (T ~ 50−100 K).
Key words: dust, extinction / ISM: molecules / ISM: general
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.