The mobility of O atoms at very low temperatures is not generally taken into account, despite O diffusion would add to a series of processes leading to the observed rich molecular diversity in space. We present a study of the mobility and reactivity of O atoms on an amorphous silicate surface. Our results are in the form of reflection absorption infrared spectroscopy and temperature-programmed desorption spectra of O2 and O3 produced via two pathways: O + O and O2 + O, investigated in a submonolayer regime and in the range of temperature between 6.5 and 30 K. All the experiments show that ozone is formed efficiently on silicate at any surface temperature between 6.5 and 30 K. The derived upper limit for the activation barriers of O + O and O2 + O reactions is ∼150 K/kb. Ozone formation at low temperatures indicates that fast diffusion of O atoms is at play even at 6.5 K. Through a series of rate equations included in our model, we also address the reaction mechanisms and show that neither the Eley–Rideal nor the hot atom mechanisms alone can explain the experimental values. The rate of diffusion of O atoms, based on modeling results, is much higher than the one generally expected, and the diffusive process proceeds via the Langmuir-Hinshelwood mechanism enhanced by tunnelling. In fact, quantum effects turn out to be a key factor that cannot be neglected in our simulations. Astrophysically, efficient O3 formation on interstellar dust grains would imply the presence of huge reservoirs of oxygen atoms. Since O3 is a reservoir of elementary oxygen, and also of OH via its hydrogenation, it could explain the observed concomitance of CO2 and H2O in the ices.
Skip Nav Destination
Article navigation
21 February 2014
Research Article|
February 19 2014
Oxygen diffusion and reactivity at low temperature on bare amorphous olivine-type silicate
M. Minissale;
M. Minissale
a)
LERMA-LAMAp,
Université de Cergy-Pontoise
, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex, France
Search for other works by this author on:
E. Congiu;
E. Congiu
LERMA-LAMAp,
Université de Cergy-Pontoise
, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex, France
Search for other works by this author on:
F. Dulieu
F. Dulieu
LERMA-LAMAp,
Université de Cergy-Pontoise
, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex, France
Search for other works by this author on:
a)
Electronic mail: marco.minissale@obspm.fr
J. Chem. Phys. 140, 074705 (2014)
Article history
Received:
October 24 2013
Accepted:
January 27 2014
Citation
M. Minissale, E. Congiu, F. Dulieu; Oxygen diffusion and reactivity at low temperature on bare amorphous olivine-type silicate. J. Chem. Phys. 21 February 2014; 140 (7): 074705. https://doi.org/10.1063/1.4864657
Download citation file:
Sign in
Don't already have an account? Register
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Sign in via your Institution
Sign in via your InstitutionPay-Per-View Access
$40.00
Citing articles via
Related Content
Formation of spinel from olivine
Appl. Phys. Lett. (March 2004)
Effect of Pressure on the Spectra of Olivine and Garnet
Journal of Applied Physics (June 2004)
Water adsorption on olivine(010) surfaces: Effect of alkali and transition metal cation doping
J. Chem. Phys. (January 2019)
Peridotite hosted chromite, magnesite and olivine deposits of West Anatolia: A review
AIP Conference Proceedings (April 2016)
The Meyer-Neldel compensation law for electrical conductivity in olivine
Appl. Phys. Lett. (December 2005)