TY - JOUR
T1 - Conduction-electron effect in quantum tunneling diffusion of hydrogen on metal surfaces
AU - Zhu, X. D.
PY - 1994
Y1 - 1994
N2 - The effective-medium theory of electrons by Norskov and Lang suggests that hydrogen adsorbed on transition metals is affected by only one-third of the electron densities when compared with interstitial hydrogen in the metals. As an important consequence, we show that the hydrogen-electron coupling parameter κ (as defined by Kondo) on W and Ni surfaces is close to 1/2 as opposed to 0.2 for interstitial hydrogen and positive muons in metals. It means that the electron-controlled under-barrier tunneling rate of hydrogen on W and Ni, proportional to T2κ-1, varies weakly with temperature. Our numerical calculation shows that the over-barrier hopping can directly cross over to electron-controlled tunneling. We thus believe that the conduction-electron mechanism is a strong candidate to explain the weakly temperature-dependent tunneling of hydrogen on W and Ni.
AB - The effective-medium theory of electrons by Norskov and Lang suggests that hydrogen adsorbed on transition metals is affected by only one-third of the electron densities when compared with interstitial hydrogen in the metals. As an important consequence, we show that the hydrogen-electron coupling parameter κ (as defined by Kondo) on W and Ni surfaces is close to 1/2 as opposed to 0.2 for interstitial hydrogen and positive muons in metals. It means that the electron-controlled under-barrier tunneling rate of hydrogen on W and Ni, proportional to T2κ-1, varies weakly with temperature. Our numerical calculation shows that the over-barrier hopping can directly cross over to electron-controlled tunneling. We thus believe that the conduction-electron mechanism is a strong candidate to explain the weakly temperature-dependent tunneling of hydrogen on W and Ni.
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U2 - 10.1103/PhysRevB.50.11279
DO - 10.1103/PhysRevB.50.11279
M3 - Article
AN - SCOPUS:0343978897
VL - 50
SP - 11279
EP - 11282
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 0163-1829
IS - 15
ER -