TY - JOUR
T1 - Diffusion on metal surfaces
T2 - Formalism and application to CO diffusion
AU - German, Ernst D.
AU - Sheintuch, Moshe
AU - Kuznetsov, Alexander M.
PY - 2008/10/2
Y1 - 2008/10/2
N2 - An analytical approach searching for the saddle point on a semiempirical adiabatic potential surface (SP-SE-APES) is proposed in order to study diffusion of adsorbed molecules on a metal surface. Three reaction coordinates are used to construct this potential surface: the perpendicular adsorption height z, the distance x between adsorption sites (top, bridge, or hollow), and coordinate θ describing phonon vibrations of the metal atoms. Harmonic approximation is used to describe the potential energy along the θ coordinate, and anharmonic Morse functions are used to describe the potential energies along z and x coordinates. The theory is applied to study CO diffusion on five transition metals (rhodium, ruthenium, palladium, iridium, and platinum), and the activation energies and the prefactors are calculated for various hopping mechanises. The one-step top-bridge-top path with the bridge state as a transition state, which was generally assumed to be the dominant mechanism of CO diffusion on these metals, is shown not to be the most likely path. Results of calculation of the diffusion coefficients are compared with experimental data.
AB - An analytical approach searching for the saddle point on a semiempirical adiabatic potential surface (SP-SE-APES) is proposed in order to study diffusion of adsorbed molecules on a metal surface. Three reaction coordinates are used to construct this potential surface: the perpendicular adsorption height z, the distance x between adsorption sites (top, bridge, or hollow), and coordinate θ describing phonon vibrations of the metal atoms. Harmonic approximation is used to describe the potential energy along the θ coordinate, and anharmonic Morse functions are used to describe the potential energies along z and x coordinates. The theory is applied to study CO diffusion on five transition metals (rhodium, ruthenium, palladium, iridium, and platinum), and the activation energies and the prefactors are calculated for various hopping mechanises. The one-step top-bridge-top path with the bridge state as a transition state, which was generally assumed to be the dominant mechanism of CO diffusion on these metals, is shown not to be the most likely path. Results of calculation of the diffusion coefficients are compared with experimental data.
UR - http://www.scopus.com/inward/record.url?scp=54349105230&partnerID=8YFLogxK
U2 - 10.1021/jp806216j
DO - 10.1021/jp806216j
M3 - 文章
AN - SCOPUS:54349105230
SN - 1932-7447
VL - 112
SP - 15510
EP - 15516
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 39
ER -