Metal binding energy shift

Figure 9.11 Promoter-induced binding energy shifts of Ar, Kr and Xe photoemission peaks with respect to adsorption on the clean metal as a function of the distance of the adsorption site to the nearest potassium atom on a potassium-promoted Rh( 111) surface. These curves reflect the variation of the surface potential (or local work function) around an adsorbed potassium atom. Note the strong and distance-dependent local work function at short distances and the constant local work function, which is lower than that of clean Rh( 111) at larger distances from potassium. The lowering at larger distances depends on the potassium coverage. The averaged distances between the potassium atoms are 1.61, 1.32 and 1.20 nm for coverages of 2.7, 4.1 and 5.0% respectively, vertical lines mark the half-way distances. Lines are drawn as a guide to the eye (adapted from Janssens et al. [38]).

Fig. 9.n Promoter-induced binding energy shifts of Ar, Kr and Xe photoemission peaks with respect to adsorption on the clean metal as a function of the distance of the adsorption site to the nearest potassium atom on a potassium-promoted Rh(lll) surface. These curves reflect the variation of the surface potential (or local work function) around an adsorbed potassium atom. Note the strong and distance-dependent local work function... 

Ley and co-workers (19) have presented quasi-experimental free atom-to-metal core level shifts for a sequence of elements, Ti through Zn. Free atom photoemission data do not exist in most of these cases, and Ley et al. used, instead, ground state calculations in which the neutral atoms were given 3dn4s2 configurations except for Cr(core level binding energy shifts,... 

For small metal clusters, the core level shifts may be explained by all of the above plus a final state effect, i.e., the charge on the ionized cluster. In an XPS experiment, it is impossible to distinguish between these different phenomena. Therefore, binding energy shifts, or a lack thereof, cannot be taken as evidence for or against an electronic interaction with the metal. 

In general, for adlayers of the Group-10 metals, one finds positive binding-energy shifts in the core levels and a decrease in the CO desorption temperature (Figure 15) [22,23]. In contrast, Cu atoms deposited on late-transition metals exhibit negative core-level shifts and an increase in the desorption temperature... 

Fig. 6.3 Binding energy shifts, SBE, of metal core levels versus fraction exposed (FE) and mean particle size, d, for various supported metal systems (data 6 and 8 are Pt-alumina). (Taken from Ref. 28.)...

Fig. 2. Binding energy shifts ABE of metal core levels measured by photoelectron spectroscopy (XPS) versus fraction exposed FE and mean particle size d for various supported metal systems (see Table II for details of the studies).

Fig. 17.2 XPS metal core level binding energy shift versus the number of metal atoms of Ru3(CO)i2, Os3(CO)i2, lr4(CO)i2 and Os6(CO)ig. The dotted curve Is a guide for the eyes.

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