Thermal desorption of water ice in the interstellar medium

By H. Fraser, M. Collings, M. McCoustra, David A. Williams. 2001

260 citations recorded by the source corpus.

Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out, potential surface reactivity, and desorption mechanisms of such molecular systems. Consequently, there is a real need from within the astronomical modelling community for accurate empirical molecular data pertaining to these processes. Here we give the first results of a laboratory programme to provide such data. Measurements of the thermal desorption of H2O ice, under interstellar conditions, are presented. For ice deposited under conditions that realistically mimic those in a dense molecular cloud, the thermal desorption of thin films (�50 molecular layers) is found to occur with zero order kinetics characterised by a surface binding energy, Edes, of 5773 ±60 K, and a pre-exponential factor, A, of 10 30±2 molecules cm 2 s 1 . These results imply that, in the dense interstellar medium, thermal desorption of H2O ice will occur at significantly higher temperatures than has previously been assumed.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Organic Chemistry

View Paper: https://www.semanticscholar.org/paper/cf89e42ca312697e87c7b11b77c34dbba1e63888

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In Astronomy and Astrophysics

1. R. Garrod
2. E. Dishoeck
3. E. Bergin
4. E. Herbst
5. K. Oberg
6. P. Caselli
7. Simon Bruderer
8. E. V. van Dishoeck

In Atomic and Molecular Physics, and Optics

1. E. Bergin
2. R. Garrod
3. H. Cuppen
4. E. Dishoeck
5. Simon Bruderer
6. E. Herbst
7. K. Oberg
8. P. Caselli

In Organic Chemistry

1. E. Dishoeck
2. E. Herbst
3. E. Bergin
4. H. Cuppen
5. R. Garrod
6. K. Oberg
7. E. V. van Dishoeck
8. H. Linnartz

Citations in the corpus

• Reaction Networks for Interstellar Chemical Modelling: Improvements and Challenges (2010, unknown): “Examples are N2 (Öberg et al. 2005), CO (Öberg et al. 2005), O2 (Acharyya et al. 2007), H2O (Bolina et al. 2005; Fraser et al. 2001), and CH3OH (Green et al. 2009).”
• Binding energies: New values and impact on the efficiency of chemical desorption (2017, unknown): “…2016) 8500 H2O2 6800 6100 6000 5700 6000 (Minissale et al. 2016) OH 5300 4800 4600 2850 4600 (Minissale et al. 2016) 3300 H2O 4600 3900 5600 5700 5600 (Fraser et al. 2001) 4815 (Sandford & Allamandola 1990) Cl 4400 3100 3000 1100 1300 1700 HCl 4800 5000 5172 5174 5172 (Olanrewaju et al.…”
• THE EFFECTS OF SNOWLINES ON C/O IN PLANETARY ATMOSPHERES (2011, background): “For all other molecules, we calculate the density-dependent sublimation temperatures following the prescription of Hollenbach et al. (2009) using binding energies of H2O, CO2 and CO of 5800 K, 2000 K and 850 K (Collings et al. 2004; Fraser et al. 2001; Aikawa et al. 1996).”
• Carbon Monoxide Entrapment in Interstellar Ice Analogs (2003, unknown): “The H2O desorption traces in each experiment (not shown) showed desorption characteristics consistent with those previously reported for clean H2O films (Fraser et al. 2001).”
• The chemical history of molecules in circumstellar disks - I. Ices (2009, background): “The pre-exponential factor,ν(X), and the binding energy,Eb(X)/k, are set to 7× 1026 cm−2 s−1 and 855 K for CO and to 1× 1030 cm−2 s−1 and 5773 K for H2O (Bisschop et al. 2006; Fraser et al. 2001).”
• PHOTODESORPTION OF ICES. II. H2O AND D2O (2008, background): “Any higher abundances require either thermal desorption of the H2O ice above ∼100 K or non-thermal desorption at lower temperatures (Bergin et al. 1995; Fraser et al. 2001).”
• Water in star-forming regions with Herschel (WISH). II. Evolution of 557 GHz 110-101 emission in low-mass protostars (2012, background): “As matter flows towards the protostar, it heats up and water desorbs when the dust temperature exceeds 100 K (Fraser et al. 2001) leading to a jump in the abundance of several orders of magnitude (Ceccarelli et al. 1996; Boonman et al. 2003).”
• Cold Dark Clouds: The Initial Conditions for Star Formation (2007, background): “Measured binding energies for CO-CO are ∼ 820 K (Collings et al. 2003) and ∼ 5800 K for H2O-H2O (Fraser et al. 2001), implying evaporation temperatures of ∼ 15 K for CO and ∼ 110 K for H2O at nH2 = 10 5 cm−3 and assuming a typical 0.1 µm grain abundance of xgr = 10 −12.”
• Grain Surface Models and Data for Astrochemistry (2017, background): “The experiments show that the molecules indeed desorb with a (close to) zeroth-order rate in the multilayer regime whereas they desorb with a (close to) first-order rate in the monolayer regime, as explained above (Fraser et al. 2001).”
• A laboratory survey of the thermal desorption of astrophysically relevant molecules (2004, methodology): “The desorption behaviour of the water-like species can thus be described by scaling the desorption kinetics of water, which have already been measured in several studies (Haynes, Tro & George 1992; Speedy et al. 1996; Fraser et al. 2001), according to the relative concentration of the species.”
• Competition between CO and N2 Desorption from Interstellar Ices (2005, background): “…kinetics of N2 and CO are zeroth order, like those of H2O, i.e., the preexponential factor will typically have a value between 1028 and 1032 molecules cm 2 s 1 (Fraser et al. 2001; Collings et al. 2003a), and the desorption rate is independent of the amount of CO or N2 adsorbed at the surface.”
• Evolution of Chemistry and Molecular Line Profiles during Protostellar Collapse (2004, methodology): “In order to reduce the water abundance in the gas to match SWAS observations (Bergin et al. 2000), we adopt a binding energy of 5700 K (Fraser et al. 2001) for water onto grain surfaces.”
• Simulation of the Formation and Morphology of Ice Mantles on Interstellar Grains (2007, methodology): “For water on amorphous ice we use 5640K, which is the result obtained by Speedy et al. (1996) and is in excellent agreement with a value of 5600 K found by Fraser et al. (2001).”
• The warm gas atmosphere of the HD 100546 disk seen by Herschel - Evidence of a gas-rich, carbon-poor atmosphere? (2012, methodology): “The hydrogenation leads to saturation of species frozen-out, from JC → JCH → JCH2 → JCH3 → JCH4, JN → JNH → JNH2 → JNH3 and JO → JOH → JH2O.”
• The molecular composition of the planet-forming regions of protoplanetary disks across the luminosity regime (2015, background): “The extent over which H2O is abundant in the disk midplane is related to the thermal desorption of H2O ice (we assume a binding energy of 5570 K, Fraser et al. 2001).”
• Chemistry as a probe of the structures and evolution of massive star-forming regions (2002, background): “As a final note, it is interesting to also consider the possibility that the CO2 desorption temperature may be greater than 100 K. Recent work by Fraser et al. (2001), suggests that the desorption temperature of water may be as high as 120–130 K.”
• Spitzer IRS Spectroscopy of IRAS-discovered Debris Disks (2006, background): “The estimated grain temperatures appear to cluster between 110 K and 130 K. Laboratory studies find that thermal desorption of water ice (H2O) from H2O layers begins at temperatures of 120 K and is completed by 170 K (Fraser et al. 2001).”