Double differential cross section for the single ionization of methane molecule by swift proton projectile

In the present work, single ionization of the methane molecule is studied. The double differential cross section for the ejected electron is considered. The target is ionized by the effect of perturbation created by proton impact with high incident velocity. In our theoretical formalism, the one Coulomb wave model is employed in the framework of the first Born approximation, which means that the final state is considered as a product of a plane wave function for the scattered heavy particle and a Coulomb wave function for the ejected electron. The initial state is a product of a plane wave function for the fast incident charge and wave functions centered over the heavy nuclei to describe the active electron. In our formalism, the one Coulomb wave model is corrected by Salin factor to take into account the effect of the electron transfer to the continuum. The obtained results are compared to the available experimental data.

Elastic Electron Scattering from Methane Molecule in the Energy Range from 50–300 eV

Electron interaction with methane molecule and accurate determination of its elastic cross-section is a demanding task for both experimental and theoretical standpoints and relevant for our better understanding of the processes in Earth’s and Solar outer planet atmospheres, the greenhouse effect or in plasma physics applications like vapor deposition, complex plasma-wall interactions and edge plasma regions of Tokamak. Methane can serve as a test molecule for advancing novel electron-molecule collision theories. We present a combined experimental and theoretical study of the elastic electron differential cross-section from methane molecule, as well as integral and momentum transfer cross-sections in the intermediate energy range (50–300 eV). The experimental setup, based on a crossed beam technique, comprising of an electron gun, a single capillary gas needle and detection system with a channeltron is used in the measurements. The absolute values for cross-sections are obtained by relative-flow method, using argon as a reference. Theoretical results are acquired using two approximations: simple sum of individual atomic cross-sections and the other with molecular effect taken into the account.

MODELING OF PATTERNS ON THE SURFACE OF GRAPHENE AND GRAPHANE

Графен - слой атомов углерода толщиной в один атом, соединенных в гексагональную решетку. А графан - это гидрогенизированный графен. Дефекты, паттерны, на их поверхностях приводят к различного рода искажениям, и, следовательно, к появлению особых свойств. В данной работе паттерны исследуются на предмет их способности избирательно улавливать молекулы в полость, а именно молекулу метана. Что касается методов моделирования, то были использованы метод молекулярной механики и полуэмпирический метод PM3. Graphene is a one-atom-thick layer of carbon atoms arranged in a hexagonal lattice. And graphane is a fully hydrogenated form of graphene. Defects are named patterns on their surfaces lead to various kinds of distortions and hence to the appearance of special properties. In this study, patterns are explored for their ability to selectively incorporate molecules namely methane molecule within the cavity. As for methods used in modeling, there are molecular mechanics and semi-empirical PM3.

Experimental analysis of the CO2/CH4 Replacement Efficiency due to Sodium Chloride Presence in Natural Gas Hydrates Reservoirs

Nowadays natural gas hydrates represent a promising opportunity for counteracting several crucial issues of the 21th century. They are a valid answer to the continuously increasing energy demand, moved by the global population growth; moreover, considering their conformation and the possibility of using them for carbon dioxide permanently storage, gas hydrates may become a carbon neutral energy source, where for each methane molecule recovered, another carbon dioxide molecule is entrapped in solid form. Considering that the combustion of one methane molecule for energy production leads to the formation of one CO2 molecule, the hydrates exploitation can be considered a clean process in terms of impact on the climate change. This work shows how the presence of sodium chloride affects the CO2/CH4 replacement process into a gas hydrates reservoir. Replacement experimental results carried out in pure demineralised water were compared with the same values performed in a mixture of water and salt, having a concentration of 37 g/l. Some parameters of interest were discussed, such us methane hydrates formed before the replacement process, total amount of hydrates (composed by both species) reached at the end of the whole process, CO2 moles that formed hydrate, quantity of hydrate present before the replacement process which were actually involved in the CO2/CH4 exchange and carbon dioxide amount which led to the formation of new hydrates structures.

Relationship between pore characteristics and occurrence state of shale gas: A case study of Lower Silurian Longmaxi shale in the Upper Yangtze Platform, South China

We have used focused ion beam-helium ion microscopy and low-pressure [Formula: see text] adsorption to investigate the pore characteristics of Lower Silurian Longmaxi shale. These results, combined with the molecular potential energy theory, reveal the relationship between pore size and the occurrence state of shale gas. Our results reveal that (1) the pore volume and the specific surface area of Lower Silurian Longmaxi shale are mainly contributed by the pores with diameters of less than 10 nm. Nanoscale organic-matter pores are predominant, and the pore surface is not generally smooth and has fractal characteristics. (2) When the distance between the methane molecule and the pore wall in organic-matter pores is limited to 2 nm, there is a strong interaction force between them, and the methane molecule is affected by the interaction force and is in the adsorbed state accordingly. When the distance between them is greater than 2 nm, the interaction force can be ignored, and the methane molecule is not affected by the interaction force and is in the free state accordingly. (3) In the pores having a radius greater than 2 nm, the adsorption capacity is positively correlated with the specific surface area; whereas in the pores having a radius smaller than 2 nm, the average gas concentration is related to the pore radius. (4) First, the adsorption-zone volume increases, and then it decreases with increasing pore diameter. When the pore diameter ranges from 1 to 6 nm, the adsorption-zone volume is significantly larger than the free-zone volume. Within this range, the adsorption volume nearly equals the pore volume. When the pore diameter ranges from 6 to 60 nm, the adsorption volume gradually decreases, whereas the free volume increases, which equals the adsorption volume when the diameter reaches 15 nm.