Isotope Effects in the Formation of Molecular Hydrogen on a Graphite Surface via an Eley−Rideal Mechanism

Abstract

The associative desorption of HD (ν,j) and D 2 (ν,j) on a graphite(0001) surface via an Eley-Rideal mechanism has been studied theoretically using a time-dependent wave packet method. We find that product molecules are formed rovibrationally excited and translationally hot. When comparing the different products to earlier calculations on the formation of H 2 on graphite(0001), we find significant isotope effects and possible resonant transitions during the reaction, which might have consequences for the possible detection of highly excited H 2 in dense intermolecular clouds.

Isotope and Surface Temperature Effects for Hydrogen Recombination on a Graphite Surface

“…[24], respectively, while the isotope effect on the adsorption of H/D on highly oriented pyrolytic graphite (HOPG) substrate was demonstrated for the first time in laboratory experiments. [25] A combined theoretical and experimental investigation on HD formation on a graphite surface was performed by Zecho et al [26] at T S = 150 K, while a theoretical approach was developed on the same system by Meijer et al [11] at T S = 10 K.…”

“…[2] Over the last few years, electronic structure calculations as well as the dynamics of H 2 , D 2 , and HD formation after hydrogen atom recombination on graphitic surfaces have been performed by different groups using various approaches. [3][4][5][6][7][8][9][10][11] These studies mainly aim to explain the great abundance of molecular hydrogen observed in the interstellar medium, so the surface temperature (T S ), when explicitly considered in the collisional models, is kept very low, between 10 and 100 K.…”

Investigation of ZPE and temperature effects on the Eley–Rideal recombination of hydrogen atoms on graphene using a multidimensional graphene–H–H potential

“…has been a subject of ongoing theoretical work over the past decade [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Interest in this topic was aroused from the astrophysical issue concerning H 2 formation in the interstellar medium (ISM).…”

“…It has been rightly argued that such characteristics are within the accuracy limits of current DFT functionals [6,11,18]. Accordingly, some works take a barrier into consideration with characteristics close to those determined by DFT calculations [9][10][11]15,17] while others consider reaction (1) as being barrier-less [1][2][3][4][5]7,8,[12][13][14][15][16]18] or nearly so [6]. The barrier in the Bachellerie-potential actually increases and moves closer towards the surface when the H b atom is displaced laterally away from the collinear approach (see Fig.…”

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.…”