相关论文: Molecular Hydrogen Formation on Amorphous Silicate…
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…
Sticking of H and D atoms on interstellar dust grains is the first step in molecular hydrogen formation, which is a key reaction in the InterStellar Medium (ISM). After studying the sticking coefficients of H2 and D2 molecules on amorphous…
Reports on the detection of carbonates in planetary nebulae (PNe) and protostars suggested the existence of a mechanism that produce these compounds in stellar winds and outflows. A consecutive laboratory study reported a possible mechanism…
Water ice is abundant both astrophysically, for example in molecular clouds, and in planetary systems. The Kuiper belt objects, many satellites of the outer solar system, the nuclei of comets and some planetary rings are all known to be…
The interactions of atomic and molecular hydrogen with bare interstellar dust grain surfaces are important for understanding H2 formation at relatively high temperatures (>20 K). We investigate the diffusion of physisorbed H atoms and the…
The synthesis of water is one necessary step in the origin and development of life. It is believed that pristine water is formed and grows on the surface of icy dust grains in dark interstellar clouds. Until now, there has been no…
An analysis of the kinetics of H2 formation on interstellar dust grains is presented using rate equations. It is shown that semi-empirical expressions that appeared in the literature represent two different physical regimes. In particular,…
Whether ice in cold cosmic environments is physically separated from the silicate dust or mixed with individual silicate moieties is not known. However, different grain models give very different compositions and temperatures of grains. The…
There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…
Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into…
We describe a phenomenological model for molecular hydrogen formation suited for applications in galaxy formation simulations, which includes on-equilibrium formation of molecular hydrogen on dust and approximate treatment of both its…
Glycoaldehyde, ethylene glycol, and methyl formate are complex organic molecules that have been observed in dark molecular clouds. Because there is no efficient gas-phase route to produce these species, it is expected that a low-temperature…
We study molecular hydrogen formation in and on solids. We construct a model with surface sites and bulk sites capable of describing (1) the motion and exchange of H and H_2 between surface and bulk, (2) the recombination of H and…
We investigated the behavior of H$_2$, main constituent of the gas phase in dense clouds, after collision with amorphous solid water (ASW) surfaces, one of the most abundant chemical species of interstellar ices. We developed a general…
Adsorption in nanoporous materials is one strategy that can be used to store hydrogen at conditions of temperature and pressure that are economically viable. Adsorption capacity of nanoporous materials depends on surface area which can be…
It has been implicitly assumed that ices on grains in molecular clouds and proto planetary disks are formed by homogeneous layers regardless of their composition or crystallinity. To verify this assumption, we observed the H2O deposition…
Context. The abundances of many observed compounds in interstellar molecular clouds still lack an explanation, despite extensive research that includes both gas and solid (dust-grain surface) phase reactions. Aims. We aim to qualitatively…
Surface chemistry on interstellar dust grains is recognized as a central component in astrochemical models, representing a plausible formation route for many of the observed complex molecular species. However, key parameters governing…
Existence of strongly bound water molecules on silicate surfaces, above the desorption temperature of water ice, has been first predicted by computational studies and recently demonstrated by laboratory experiments. Such trapped water may…
The diffusion of atoms and molecules in ices covering dust grains in dense clouds in interstellar space is an important but poorly characterized step in the formation of complex molecules in space. Here we report the measurement of…