Time-Dependent Quantum Mechanical Calculations on the Formation of Molecular Hydrogen on a Graphite Surface via an Eley−Rideal Mechanism

Abstract

The associative desorption of H2 (ν,j) on a graphite(0001) surface via an Eley−Rideal mechanism has been studied theoretically. In our calculations we used a time-dependent wave packet method treating three degrees of freedom quantum mechanically. A newly developed potential energy surface based on plane-wave density functional calculations was employed. In our 3D calculations we find less vibrational excitation for the product H2 molecules than in calculations that used only two degrees of freedom. However, the product H2 molecules are formed rotationally excited. This could have important implications for the chemistry of H2 in the interstellar medium and the interpretation of astronomical data.

Interstellar H adsorption and H2formation on the crystalline (010) forsterite surface: a B3LYP-D2* periodic study

“…coronene clusters and C(0001) surfaces) have been published, [12][13][14][15] generally predicting a high reaction probability and significant ro-vibration populations in nascent molecules, in agreement with the experimental findings. 16 Usually, effects due to the presence of porous and point defects were not accounted for.…”

Kinetic Monte Carlo studies of hydrogen abstraction from graphite

“…Since a considerable fraction of the interstellar grains is expected to consist of carbonaceous material, a popular model system for this process is hydrogen abstraction from graphite. This Eley-Rideal reaction has been studied by Density Functional Theory (DFT) and Quantum Wave packet calculations [14,15,16,17,18,19]. Based on these calculations several different mechanisms have been proposed to contribute to the Eley-Rideal abstraction process.…”

“…Based on these calculations several different mechanisms have been proposed to contribute to the Eley-Rideal abstraction process. These include: Direct Eley-Rideal [14,15,16,17,18,19], barrierless abstraction of one hydrogen atom forming part of a para-dimer configuration [20] and abstraction by rapidly diffusing H atoms in physisorbed states [21].…”

Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

“…Hydrogen adsorption on carbon based materials such as graphite and graphene is relevant to hydrogen storage, 9 band gap engineering, [10][11][12][13] and potentially as the first step in H 2 formation in the interstellar medium. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Although there is enormous interest in H adsorption on carbonaceous surfaces, with graphene, graphite and polycyclic aromatic hydrocarbons (PAHs) being the most widely studied model systems, we still don't fully understand the seemingly simple process of how a single H atom adsorbs on the surface.…”