2.3 Factors Determining the Work Function
21
Fig. 2.15 Relationship between step density and work function values [12] (see text for explanation)
Table 2.3 Influence of geometric surface state on measured work function for Pt and Rh
Element Terrace plane {hkl} Geometric surface
state
Measured terrace
work function (eV)
Literature work
function (eV)
Pt
{111}
Smooth
6.22 , 6.0
5.99, 5.95
5.93
{111}
Roughened
5.53
(100}
Smooth
6.00
5.84, 5.81
5.8
(110}
Smooth
5.35
5.49, 5.4
(110}
Roughened
5.24
–
Rh
{111}
Smooth
–
5.62, 5.3
{111}
Roughened
4.95
–
{100}
Smooth
5.38
5.36
{110}
Smooth
4.80
4.89, 4.8
{110}
Roughened
4.70
–
See Ref. [13] for the references of the literature work function in the table
When an adsorbed atom species is different from the species of the substrate
in the above growth situation (heteroepitaxy, not homoepitaxy), the initial step is
regarded as the adsorption of heteroatoms. In practice, contaminant atoms are often
adsorbed, which affects the work function to a large extent. The change in the work