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Molecular dynamics simulation of Pt on a vitreous silica surface
A679 V. KUMYKOV * and A. IGNATIEV Department Received
of Physics, University of Houston, Houston, Texas 77004, USA 12 September
1984; accepted
for publication
5 June 1985
The temperature dependence of low-energy electron diffraction intensity-energy spectra from the graphite (0001) surface has been measured from 100 to 600 K. The perpendicular and parallel effective surface Debye temperatures and the effective mean-square vibration amplitudes as a function of electron energy have been determined from these data. The values show surface enhancement and approach the bulk values with increasing electron energy. At energies below - 100 eV, however, there is little anisotropy observed between the effective Debye temperatures parallel and perpendicular to the graphite surface.
Surface Science 163 (1985) 59-66 North-Holland, Amsterdam
MOLECULAR DYNAMICS SILICA SURFACE
59
SIMULATION
OF Pt ON A VITREOUS
S.M. LEVINE and S.H. GAROFALINI Department Received
of Ceramics, Rutgers Universrty, Piscataway,
11 January
New Jersey 08854, USA
1985
The molecular dynamics (MD) computer simulation technique was used to simulate the deposition and cluster growth processes of Pt on a vitreous silica surface. Using a combination of a modified Born-Mayer-Huggins potential (for the substrate) and a Lennard-Jones potential (for the adatoms), the structural features of clusters resulting from four different deposition processes were analyzed and compared to EXAFS results of a similar system. Two of the four deposition processes allowed cluster growth with little interaction with the substrate (by physical separation) and showed comparable results to the EXAFS data. In the two remaining deposition processes, cluster formation occurring with increasing interaction with the substrate resulted in smaller, less three-dimensional particles. This result is in accordance with experimental and theoretical calculations suggesting limited mobility of metal atoms to diffuse once in contract with the amorphous surface.
Surface Science 163 (1985) 67-78 North-Holland, Amsterdam
67
ENERGY DEPENDENCE OF THE SURFACE COMPOSITION IN Au-Cu ALLOYS UNDER Ar + ION BOMBARDMENT *
CHANGES
Ri-Sheng LI, Li-Xun TU and Yu-Zhen SUN Institute of Metal Research, Academia Sinica, Shenyang I lOOIS, People’s Rep. of China Received
14 February
1985; accepted
for publication
29 May 1985
The energy-dependence of the surface composition changes in Au-Cu alloys under Ar + ion bombardment has been studied. When the energy of the Ar+ ions is higher than 1 keV, the surface concentration of gold decreases with bombardment time gradually approaching the steady state
of Physics, University of Houston, Houston, Texas 77004, USA 12 September
1984; accepted
for publication
5 June 1985
The temperature dependence of low-energy electron diffraction intensity-energy spectra from the graphite (0001) surface has been measured from 100 to 600 K. The perpendicular and parallel effective surface Debye temperatures and the effective mean-square vibration amplitudes as a function of electron energy have been determined from these data. The values show surface enhancement and approach the bulk values with increasing electron energy. At energies below - 100 eV, however, there is little anisotropy observed between the effective Debye temperatures parallel and perpendicular to the graphite surface.
Surface Science 163 (1985) 59-66 North-Holland, Amsterdam
MOLECULAR DYNAMICS SILICA SURFACE
59
SIMULATION
OF Pt ON A VITREOUS
S.M. LEVINE and S.H. GAROFALINI Department Received
of Ceramics, Rutgers Universrty, Piscataway,
11 January
New Jersey 08854, USA
1985
The molecular dynamics (MD) computer simulation technique was used to simulate the deposition and cluster growth processes of Pt on a vitreous silica surface. Using a combination of a modified Born-Mayer-Huggins potential (for the substrate) and a Lennard-Jones potential (for the adatoms), the structural features of clusters resulting from four different deposition processes were analyzed and compared to EXAFS results of a similar system. Two of the four deposition processes allowed cluster growth with little interaction with the substrate (by physical separation) and showed comparable results to the EXAFS data. In the two remaining deposition processes, cluster formation occurring with increasing interaction with the substrate resulted in smaller, less three-dimensional particles. This result is in accordance with experimental and theoretical calculations suggesting limited mobility of metal atoms to diffuse once in contract with the amorphous surface.
Surface Science 163 (1985) 67-78 North-Holland, Amsterdam
67
ENERGY DEPENDENCE OF THE SURFACE COMPOSITION IN Au-Cu ALLOYS UNDER Ar + ION BOMBARDMENT *
CHANGES
Ri-Sheng LI, Li-Xun TU and Yu-Zhen SUN Institute of Metal Research, Academia Sinica, Shenyang I lOOIS, People’s Rep. of China Received
14 February
1985; accepted
for publication
29 May 1985
The energy-dependence of the surface composition changes in Au-Cu alloys under Ar + ion bombardment has been studied. When the energy of the Ar+ ions is higher than 1 keV, the surface concentration of gold decreases with bombardment time gradually approaching the steady state