Changes in the morphology of interstellar ice analogues after hydrogen atom exposure

Details Changes in the morphology of interstellar ice analogues after hydrogen atom exposure Changes in the morphology of interstellar ice analogues after hydrogen atom exposure

2010-11-24

arxiv.org/abs/1011.5344v2

Astronomy and Astrophysics

Astrophysics

Galaxy Astrophysics

9 pages, 7 figures, submitted to PCCP

Scientific paper

10.1039/C0CP01462A

The morphology of water ice in the interstellar medium is still an open question. Although accretion of gaseous water could not be the only possible origin of the observed icy mantles covering dust grains in cold molecular clouds, it is well known that water accreted from the gas phase on surfaces kept at 10 K forms ice films that exhibit a very high porosity. It is also known that in the dark clouds H2 formation occurs on the icy surface of dust grains and that part of the energy (4.48 eV) released when adsorbed atoms react to form H2 is deposited in the ice. The experimental study described in the present work focuses on how relevant changes of the ice morphology result from atomic hydrogen exposure and subsequent recombination. Using the temperature-programmed desorption (TPD) technique and a method of inversion analysis of TPD spectra, we show that there is an exponential decrease in the porosity of the amorphous water ice sample following D-atom irradiation. This decrease is inversely proportional to the thickness of the ice and has a value of Phi_0 = 2 x 10^16 D-atoms/cm^2 per layer of H2O. We also use a model which confirms that the binding sites on the porous ice are destroyed regardless of their energy depth, and that the reduction of the porosity corresponds in fact to a reduction of the effective area. This reduction appears to be compatible with the fraction of D2 formation energy transferred to the porous ice network. Under interstellar conditions, this effect is likely to be efficient and, together with other compaction processes, provides a good argument to believe that interstellar ice is amorphous and non-porous.

Affiliated with

Also associated with

No associations

Rating

Changes in the morphology of interstellar ice analogues after hydrogen atom exposure does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Changes in the morphology of interstellar ice analogues after hydrogen atom exposure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Changes in the morphology of interstellar ice analogues after hydrogen atom exposure will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-240769