TY - JOUR
T1 - Impact of Oxygen Chemistry on Model Interstellar Grain Surfaces
AU - Rosu-Finsen, Alexander
AU - McCoustra, Martin R. S.
N1 - Invited Contribution to Special Issue
PY - 2018/2/28
Y1 - 2018/2/28
N2 - Temperature-programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS) are used to probe the effect of atomic and molecular oxygen (O and O2) beams on amorphous silica (aSiO2) and water (H2O) surfaces (porous-amorphous solid water; p-ASW, compact amorphous solid water; c-ASW, and crystalline ice; CI). Altering the deposition method of O2 is shown to result in different desorption energies of O2 due to differences in O2 film morphology when deposited on the aSiO2 surface. O2 enthalpy of formation is dissipated into the aSiO2 substrate without changes in the silica network. However, on the H2O surfaces, O2 formation enthalpy release is dissipated into the H-bonded matrix leading to morphological changes, possibly compacting p-ASW into c-ASW while CI appears to undergo amorphisation. The enthalpy release from O2 formation is, however, not enough to result in reactive desorption of O2 or H2O under the current experimental circumstances. Further to this, O2 formation on sub-monolayer quantities of H2O leads to enhanced de-wetting and a greater degree of H-bond reconnection in H2O agglomerates. Lastly, O3 is observed from the O + O2 reaction on all surfaces studied.
AB - Temperature-programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS) are used to probe the effect of atomic and molecular oxygen (O and O2) beams on amorphous silica (aSiO2) and water (H2O) surfaces (porous-amorphous solid water; p-ASW, compact amorphous solid water; c-ASW, and crystalline ice; CI). Altering the deposition method of O2 is shown to result in different desorption energies of O2 due to differences in O2 film morphology when deposited on the aSiO2 surface. O2 enthalpy of formation is dissipated into the aSiO2 substrate without changes in the silica network. However, on the H2O surfaces, O2 formation enthalpy release is dissipated into the H-bonded matrix leading to morphological changes, possibly compacting p-ASW into c-ASW while CI appears to undergo amorphisation. The enthalpy release from O2 formation is, however, not enough to result in reactive desorption of O2 or H2O under the current experimental circumstances. Further to this, O2 formation on sub-monolayer quantities of H2O leads to enhanced de-wetting and a greater degree of H-bond reconnection in H2O agglomerates. Lastly, O3 is observed from the O + O2 reaction on all surfaces studied.
UR - https://www.scopus.com/pages/publications/85042611832
U2 - 10.1039/C7CP05480G
DO - 10.1039/C7CP05480G
M3 - Article
SN - 1463-9076
VL - 20
SP - 5368
EP - 5376
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 8
ER -