AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS3-WeA

Paper SS3-WeA8
Soft X-ray Photoelectron Spectroscopy Studies of Faceting and Alloying for Ultra Thin Films of Ruthenium on W(111) and W(211)

Wednesday, October 4, 2000, 4:20 pm, Room 210

Session: Surface and Interface Structure I
Presenter: G.J. Jackson, Rutgers University
Authors: G.J. Jackson, Rutgers University
J.E. Rowe, North Carolina State University
T.E. Madey, Rutgers University
Correspondent: Click to Email
High resolution soft X-ray photoelectron spectroscopy (using synchrotron radiation) and low energy electron diffraction (LEED), have been used to study alloying and faceting of Ru dosed onto W single crystal surfaces. W 4f core-level photoemission spectra and valence band spectra have been measured at various photon energies for W(111) and W(211), this photoemission being collected along the surface normal and at shallow grazing angles. The ultrathin film growth and evolution before and after annealing, on both W surfaces, has been investigated for coverages ranging from 0 to greater than 3 physical monolayers. After annealing multilayers of Ru on W(211) at low temperature (600 K), core-level shifts in the W 4f photoemission indicate formation of a Ru/W alloy that may be subsurface. Upon annealing to higher temperatures (600-1600 K), the core-level shifts reveal a concentrated Ru/W alloy. For the W(111) surface, previous studies from several other 4d and 5d dosed metals have shown that the ultrathin film covered surface forms nanoscale pyramidal facets with (211) faces. However, our LEED observations provide no evidence that Ru induces faceting of W(111). W 4f core-level shifts and their relative photoelectron intensities have indicated that clustering may occur on the W(111) surface after annealing. The results from studies of the Ru investigations are closely compared with previous studies from Pt,Pd,Ir,Rh dosed onto W(111) and W(211). In these cases it has been shown that fractional monolayer coverages do not form alloys and that for coverages exceeding 1 ML, the W atoms can dissolve into the adsorbed layer. Our results indicate some differences in the thermal stability of Ru/W, compared with Pt,Pd,Ir, Rh on W.