Binding energy shifts

This case is particularly interesting since the surface segregation energy can be directly compared to surface core level binding energy shifts (SCLS) measurements. Indeed, if we assume that the excited atom (i. e., with a core hole) is fully screened and can be considered as a (Z + 1) impurity (equivalent core approximation), then the SCLS is equal to the surface segregation energy of a (Z + 1) atom in a Z matrixi. in this approximation the SCLS is the same for all the core states of an atom. 

W. F. Egelhoff Jr., Thermochemical Values for Cu-Ni Surface and Interface Segregation Deduced from Core-Level Binding Energy Shifts, Phys. Rev. Lett. 50 587 (1983)... 

Shift in XPS Surface Core Binding Energy Shift in CO TPD maximum... 

Bjomeholm O, Nilsson A, Tillborg H, Bennich P, Sandell A, Hemnas B, Puglia C, Martensson N. 1994. Overlayer stmcture from adsorbate and substrate core level binding energy shifts CO, CCH3 and O on Pt(lll). Surf Sci 315 L983-L989. 

It is also possible that Pd is reduced to a second PdHx phase. When the metalhc Pd chemical shift was compared to PdHx as reported in the hterature (13), the core level Pd 3d5/2 binding energy shift was only 0.2 eV. The article also found that the asyimnetiy of the 3d peak was slightly reduced, and a shakeup satellite peak (indicated by the arrow in Figure 15.6) disappeared. However, in the presence of metalhc Pd, we cannot determine whether a second PdHx phase is present. 

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]).

Lindberg et al.17 have shown that the carbon Is shifts of some substituted benzenes are linearly correlated with the Hammett a parameters of the substituents. However, Hammett parameters are of rather limited applicability a given set of a values can be used to correlate data only for similar chemical systems. It has recently been shown18 that a wider variety of core binding energy shifts can be correlated by the four-parameter relation... 

Table 3. Some carbon Is binding energy shifts calculated using the equivalent cores approximation...

While the area ratio apparently eliminates the non-classical ion, one must ask whether the small binding energy shift observed can be accounted for if the ion is classical. This might be possible because the shift is dependent on a large number of factors which differ... 

ML c(2 x 2) ordered phase corresponds to the coverage beyond which this transition occurs, but photoelectron and vibrational spectroscopic studies show that there is typically co-occupation of both states when the well-ordered c(2 x 2) LEED pattern is seen. The use of the photoelectron binding energy shifts in the PhD... 

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... 

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