Related papers: Oxygen diffusion and reactivity at low temperature…
To help provide insight into the remarkable catalytic behavior of the oxygen/silver system for heterogeneous oxidation reactions, purely sub-surface oxygen, and structures involving both on-surface and sub-surface oxygen, as well as…
Physisorbed atoms on the surface of interstellar dust grains play a central role in solid state astrochemistry. Their surface reactivity is one source of the observed molecular complexity in space. In experimental astrophysics, the high…
A prevailing theory for the interstellar production of complex organic molecules (COMs) involves formation on warm dust-grain surfaces, via the diffusion and reaction of radicals produced through grain-surface photodissociation of stable…
The formation of CO2 in quiescent regions of molecular clouds is not yet fully understood, despite CO2 having an abundance of around 10-34 % H2O. We present a study of the formation of CO2 via the non-energetic route CO + OH on non-porous…
The formation and growth of refractory matter on pre-existing interstellar dust grain surfaces was studied experimentally by annealing neon-ice matrices in which potential precursors of silicate grains (Mg and Fe atoms, SiO and SiO$_2$…
We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using HIFI on…
Dust particles in protoplanetary disks experience various chemical reactions under different physicochemical conditions through their accretion and diffusion, which results in the radial chemical gradient of dust. We performed…
Context. The chemistry of the diffuse interstellar medium rests upon three pillars: exothermic ion-neutral reactions (" cold chemistry "), endothermic neutral-neutral reactions with significant activation barriers (" warm chemistry "), and…
We present a detailed first-principles study which explores the configurational space along the relevant reactions and migration paths involving the formation and dissociation of interstitial carbon-oxygen complexes, $\mathrm{C_{i}O_{i}}$…
We present the results of large scale computer simulations in which we investigate the static and dynamic properties of sodium disilicate and sodium trisilicate melts. We study in detail the static properties of these systems, namely the…
Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They…
Absorbing UV radiation, ozone protects life on Earth and plays a fundamental role in Earth's temperature balance. The formation of ozone occurs through the ternary recombination reaction: O$_2$+O+M $\rightarrow$ O$_3$+M, where M can be…
To help understand the high activity of silver as an oxidation catalyst, e.g., for the oxidation of ethylene to epoxide and the dehydrogenation of methanol to formaldehyde, the interaction and stability of oxygen species at the Ag(111)…
We construct a theoretical model for low-temperature crystallization of amorphous silicate grains induced by exothermic chemical reactions. As a first step, the model is applied to the annealing experiments, in which the samples are (1)…
Interstellar complex organic molecules (COMs) are commonly observed during star formation, and are proposed to form through radical chemistry in icy grain mantles. Reactions between ions and neutral molecules in ices may provide an…
The chemical changes of Ti/Er/n-Si(100) stacks evaporated in high vacuum and grown ex situ by rapid thermal annealing were scrutinized. The emphasis was laid on the evolution with the annealing temperature of (i) the Er-Si solid-state…
Here we report the results of an experimental and theoretical study of the gas-phase reactions between O($^1$D) and H$_2$O and O($^1$D) and D$_2$O at room temperature and below. On the experimental side, the kinetics of these reactions have…
The amorphous aluminium silicate (Al2O3)2(SiO2) [AS2] is investigated by means of large scale molecular dynamics computer simulations. We consider fully equilibrated melts in the temperature range 6100K >= T >= 2300K as well as glass…
In cold molecular clouds, UV photolysis of icy grain mantles generates radicals that lead to new molecule formation. When radical diffusion is limited by low temperatures, oxygen atom addition and insertion reactions, enabled by photolysis…
A full understanding of glasses requires an accurate atomistic picture of the complex activated processes that constitute the low-temperature dynamics of these materials. To this end, we generate over five thousand activated events in…