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PCCP_Peeling the Astronomical Onion_Accepted Version.pdf (410.67 kB)

Peeling the astronomical onion

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journal contribution
posted on 2023-06-09, 04:06 authored by Alexander Rosu-Finsen, Demian Marchione, Tara L Salter, James StubbingJames Stubbing, Wendy BrownWendy Brown, Martin R S McCoustra
Water ice is the most abundant solid in the Universe. Understanding the formation, structure and multiplicity of physicochemical roles for water ice in the cold, dense interstellar environments in which it is predominantly observed is a crucial quest for astrochemistry as these are regions active in star and planet formation. Intuitively, we would expect the mobility of water molecules deposited or synthesised on dust grain surfaces at temperatures below 50 K to be very limited. This work delves into the thermally-activated mobility of H2O molecules on model interstellar grain surfaces. The energy required to initiate this process is studied by reflection-absorption infrared spectroscopy of small quantities of water on amorphous silica and highly oriented pyrolytic graphite surfaces as the surface is annealed. Strongly non-Arrhenius behaviour is observed with an activation energy of 2 kJ mol-1 on the silica surface below 25 K and 0 kJ mol-1 on both surfaces between 25 and 100 K. The astrophysical implication of these results is that on timescales shorter than that estimated for the formation of a complete monolayer of water ice on a grain, aggregation of water ice will result in a non-uniform coating of water, hence leaving bare grain surface exposed. Other molecules can thus be formed or adsorbed on this bare surface.

Funding

Evolution of ices: From molecular cloud to ocean; G1613; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/M000869/1

History

Publication status

  • Published

File Version

  • Accepted version

Journal

Physical Chemistry Chemical Physics

ISSN

1463-9076

Publisher

Royal Society of Chemistry

Issue

46

Volume

18

Page range

31930-31935

Department affiliated with

  • Chemistry Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2016-11-22

First Open Access (FOA) Date

2017-11-09

First Compliant Deposit (FCD) Date

2016-11-19

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