O₂ formation in cold environments

Abstract

Oxygen recombination in side amorphous solid water.

Energy Redistribution Following CO2 Formation on Cold Amorphous Solid Water

“…The simulation system, Figure 1 , consisted of an equilibrated cubic box of amorphous solid water with dimension 31 × 31 × 31 Å 3 containing 1000 water molecules. As all bonds and angles are flexible, the simulations were run with a time step of Δ t = 0.1 fs and the non-bonded cutoff was at 13 Å. Simulations were started from an existing, equilibrated ASW structure ( Pezzella et al, 2018 ; Pezzella and Meuwly, 2019 ; Upadhyay et al, 2021 ) by adding CO A and O B inside ( Figure 1A ) or on top of ( Figure 1B ) ASW.…”

“…( Minissale et al, 2016b ). For CO, MD simulations reported ( Pezzella and Meuwly, 2019 ) desorption energies between 3.1 and 4.0 kcal/mol (1560–2012 K or 130–170 meV), compared with 120 meV from experiments. ( Karssemeijer et al, 2013 ).…”

“…The high porosity of ASW ( Bossa et al, 2014 ; Bossa et al, 2015 ; Cazaux et al, 2015 ) makes it a good catalyst for gas-surface reactions involving oxygen ( Ioppolo et al, 2011a ; Romanzin et al, 2011 ; Chaabouni et al, 2012 ; Minissale et al, 2013a ; Dulieu et al, 2017 ; Pezzella et al, 2018 ; Pezzella and Meuwly, 2019 ; Christianson and Garrod, 2021 ), hydrogen ( Hama and Watanabe, 2013 ), carbonaceous ( Minissale et al, 2013b ; Minissale et al, 2016a ; Qasim et al, 2020 ; Molpeceres et al, 2021 ) and nitrogen-containing ( Minissale et al, 2014 ) species and helps maintaining those species on ( Minissale et al, 2019 ) or inside ASW. ( Minissale et al, 2016b ; Tsuge et al, 2020 ).…”

“…It was also found that the CO desorption energy from ASW depends on CO coverage with ranges from E des = 1700 K for low to 1000 K for high coverage ( He et al, 2016 ) which is consistent with the simulations. ( Pezzella and Meuwly, 2019 ). On non-porous and crystalline water surfaces submonolayer desorption energies for CO are 1307 and 1330 K ( meV), respectively.…”

Energy Redistribution following CO$_2$ Formation on Cold Amorphous Solid Water

“…4 Under laboratory conditions the water ices seem to be amorphous 5 whereas the morphology of ices in the interstellar medium are more debated. 6 The high porosity of ASW [7][8][9] makes it a good catalyst for gas-surface reactions involving oxygen, [10][11][12][13][14][15][16] hydrogen, 17 carbonaceous 18,19 and nitrogen-containing 20 species and helps maintaining those species on or inside ASW. 21,22 This increases the probability for the reaction partners to diffuse to locations for collisions and association reactions to occur.…”