Isotope effects on direct and indirect processes of hydrogen abstraction from Cu(111)

Abstract

We investigate and discuss isotope effects on hydrogen abstraction from Cu(111) by performing quantum dynamics calculations that consider both direct (an impinging hydrogen atom directly abstracts an adsorbed hydrogen atom) and indirect (the impinging hydrogen atom diffuses across the surface before it abstracts an adsorbed hydrogen atom) processes quantum mechanically. Our calculation results show that the abstraction reaction probabilities P reac are 0.742(D-on-D) > 0.640(H-on-D) > 0.594(H-on-H) > 0.533(D-on-H). (Note that the term 'X-on-Y' indicates abstraction of Y atoms adsorbed on the surface by gas-phase X atoms.) Furthermore, the mean normal translational and vibrational energies for H-on-D are larger than those for D-on-H, while the mean parallel translational energy for D-on-H is comparable with that for Hon-D. This implies that the decrease in the abstraction reaction probability for D-on-H, as compared with that for H-on-D, is mainly due to the decrease in the frequency of occurrence of the direct process in abstraction reactions.

Molecular Orientation and Surface Site Dependence of the Dissociative Adsorption of O$_{2}$/Al(111)

“…We can see that the sticking probability became higher for higher initial vibrational state of the molecule in accordance with the experiment. This shows the evolution of the vibrational assisted sticking (VAS) effect, which is already familiar to H 2 molecule [21]. As shown in PES in Fig.…”

H(D) → D(H) + Cu(111) collision system: Molecular dynamics study of surface temperature effects

“…Therefore, as expected, the molecular desorption processes are obviously exothermic by more than 2 eV. There are a number of theoretical and experimental studies of these types on Cu, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and on different metal surfaces, such as Ni, [19][20][21][22][23][24] Pt, [25][26][27] Al, 28 Si. 29 These studies and our present work suggest that rates of all the reaction channels and their mechanisms can differ from metal to metal and also vary on different faces of the same metal.…”