Shake-up features

Figure 4 Schematic electron energy level diagram (a) of a core-level photoelectron ejection process (one electron process) (b) core-level photoelectron ejection process with shake-up (two- electron process) (c) schematic XPS spectrum from (a) plus (b) (d) Cu 2pa/2 XPS spectrum for Cu in CU2O and Cu in CuO. The latter shows strong shake-up features.

The x-ray photoelectron spectra for both dissolved and solventless polyamic acid have been reported in the literature [2-8], It has been noted previously by us [5-7], that the spectra for solventless PAA and PI exhibit a pronounced deficiency for the Cls and Ols carbonyl emission. This, together with an analysis of the Nls lineshape and the Ols and Cls shake up features, allows us to derive conclusions on the chemical nature of solventless polyamic acid and to explain it s high reactivity towards metals as discussed below. 

A different interpretation is favoured for the chromium on polyimide data by Jordan et al. [21], who propose that initial attack of chromium and charge transfer occurs on the carbonyl moiety. Since the charge transferred from the metal is distributed over the planar PMDA moiety of the polyimide, the core level spectra by themselves will not allow a distinction between the two models proposed. However, a careful analysis of the shake up features in the Cls, Ols and Nls core hole spectra might reveal the initial binding site when the amplitude distributions of the LUMO s and HOMO S in the system relative to the created core hole are considered. 

Combining all the results from the UPS, S 2p, N Is, C Is core levels and its shake-up features of the XPS, it is manifested that Cs favorably interacts with the N atoms of the F8BT and at the same time it brings electronic modification to the polymer that may be undesirable in PLED fabrication. Our findings also suggest that the F8BT possesses two distinct interfaces when interacted with Cs and Ca, which have never been observed in the case of PFO. 

From the inset of Fig. 5.20(c), we observe clearly the alternation of the shake-up features of the C Is core level upon CsF and Yb deposition. The CsF deposition does not affect the shake-up peaks, but 3 A of Yb immediately destroys one of them at a lower binding energy. This result is analogous to that obtained at the Cs/PFO and Cs/F8BT interfaces, indicating that the LUMO is broadened by the metal deposition by a charge-transfer process. Therefore, unlike the case of Yb/CsF/Au, the liberated Cs is not in the metallic state and instead it immediately... 

Figure 18. Shake-up features in XPS Cu 2p spectra recorded from Cu metal. CuO and CUSO4, (From Ref. 18.)...

Figure 16A shows a stackplot of XP spectra of the Cu 2p core regions acquired from these surfaces after AFM imaging. Shake-up features at 945 and 965 eV for the Cu 2p3/2 and 2pi/2 core levels are evident and are diagnostic of an open 3d shell of Cu(+2). The peak positions and relative intensities of the satellites from these levels are indicative of the presence of CuO at the surface. The relative intensities of the shake-up lines to the main core level of both the Cu 2p3/2 and 2pi/2 levels varied as a function of Cu(ac)2 solution concentration. The shake-up intensities denoting CuO on the surface were relatively more intense at higher Cu(ac)2 concentration. 

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