Related papers: Molecular hydrogen formation on grain surfaces
There exists much uncertainty surrounding interstellar grain-surface chemistry. One of the major reaction mechanisms is grain-surface diffusion for which the the binding energy parameter for each species needs to be known. However, these…
Oxyhydrides have drawn attention because of their fast ion conductivity and strong reducing properties. Recently, hydride ion migration in SrTiO$_{3-x}$H$_{x}$ oxyhydride crystals has been investigated, showing that hydride ion migration is…
The majority of hydrogen in the interstellar medium (ISM) is in atomic form. The transition from atoms to molecules and, in particular, the formation of the H$_2$ molecule, is a key step in cosmic structure formation en route to stars.…
A model is presented for obtaining the step formation energy for metallic islands on (111) surfaces from Monte Carlo simulations. This model is applied to homo (Cu/Cu(111), Ag/Ag(111)) and heteroepitaxy (Ag/Pt(111)) systems. The embedded…
Photoelectrons, the fast electrons produced in the photoionization of planetary atmospheres, drive transformations in the atmospheric gas that are often inhibited by energy considerations for thermal electrons. The transformations include…
Detailed semi-empirical interaction potential calculations are performed to determine the potential energy surface experienced by the molecules CO, HCN, H2O and H2CO, when adsorbed on the basal plane (0001) of graphite at low temperature.…
Evolution of grain mantles in various interstellar environment is studied. We concentrate mainly on water, methanol, carbon di-oxide, which constitute nearly 90% of the grain mantle. We investigate how the production rates of these…
A model is proposed for the formation of water ice mantles on grains in interstellar clouds. This occurs by direct accretion of monomers from the gas, be they formed by gas or surface reactions. The model predicts the existence of a…
Many theoretical and laboratory studies predict H2 to be formed in highly excited ro-vibrational states. The consequent relaxation of excited levels via a cascade of infrared transitions might be observable in emission from suitable…
Ionic Liquids (ILs) provide a promising solution for CO$_2$ capture and storage to mitigate global warming. However, identifying and designing the high-capacity IL from the giant chemical space requires expensive, and exhaustive simulations…
We present a two-dimensional granular model for the mechanical behavior of an ensemble of globular grains, during solidification. The grain structure is produced by a Voronoi tessellation based on an array of predefined nuclei. We consider…
The expression of chirality in adsorption phenomena constitutes an important topic, not only relevant to asymmetric transformations involving solid surfaces, but also to the emergence of homochirality in both terrestrial and…
We investigate the formation and evolution of interstellar dust-grain ices under dark-cloud conditions, with a particular emphasis on CO2. We use a three-phase model (gas/surface/mantle) to simulate the coupled gas--grain chemistry,…
The observed gas-phase molecular inventory of hot cores is believed to be significantly impacted by the products of chemistry in interstellar ices. In this study, we report the construction of a full macroscopic Monte Carlo model of both…
This paper establishes a data-driven modeling framework for lean Hydrogen (H2)-air reaction rates for the Large Eddy Simulation (LES) of turbulent reactive flows. This is particularly challenging since H2 molecules diffuse much faster than…
We propose a simple and reliable method to study the translational relaxation of 'hot' H atoms following their production by chemical mechanisms. The problem is relevant to PDR's, shocks, photospheres, atmospheric entry problems. We show…
Back-diffusion is the phenomenon by which random walkers revisit binding sites on a lattice. This phenomenon must occur on interstellar dust particles, slowing down dust-grain reactions, but it is not accounted for by standard rate-equation…
Thin films of the high-temperature superconductor HgBa$_2$CaCu$_2$O$_{6+\delta}$ have been prepared on SrTiO$_3$ substrates by pulsed-laser deposition of precursor films and subsequent annealing in mercury-vapor atmosphere. The…
This paper provides detailed comparisons of chemical reaction mechanisms of H2 applicable at high preheat temperatures and pressures relevant to gas turbine and particularly Alstom's reheat gas turbine conditions. It is shown that the…
We report on the first results of experiments to measure the recombination rate of hydrogen on surfaces of astrophysical interest. Our measurements give lower values for the recombination efficiency (sticking probability S x probability of…