Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
62 (1987), S. 1887-1894
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Appearance potential spectroscopy has been applied to the investigation of the relation between work function and surface composition for a sputter-formed alloy of Re-1% Pd. This approach permits point-by-point estimates of the work function to be compared to corresponding measurements of surface composition. Developed techniques permit the use of nonlinear regression to analyze appearance potential and scanning Auger microprobe data from a single line scan on the Topping model of dipole layer formation. Resistively heated samples suffer segregation of Pd to the alloy surface and consequent increase in work function, with the amount of increase dependent upon the Pd-to-Re ratio at the surface. Preliminary results yielded different Topping parameters for low- and high-coverage regions. Values for dipole moment at zero electric field P0 and polarizability α are [P0,α]=[(6.1±1.5)×10−30 C m, (14.6±6.6) A(ring)3] or [(1.7±0.6)×10−30 C m, (1.4±0.4)A(ring)3], with Pd/Re less than or greater than 0.7, respectively. When the surface concentration of Pd is at least 0.2, a local increase in O concentration causes a local reduction of the work function on an otherwise clean alloy surface. On pure Re, or on a surface with substantial concentrations of other metallic impurities, oxygen adsorption causes an increase in work function. It is suggested that the appearance potential technique may be of value to the study of catalysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.339574
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