N Is XPS spectra

The relative instrumental sensitivity factors for cobalt and nitrogen were determined by measuring core level (Co 2p and N Is) XPS spectra for a series of pure cobalt amine complexes of established stoichiometry. To evaluate the core level photopeak intensities, peak areas, including shake-up satellite intensity were used. The precision for the measurements of the nitrogen to cobalt atomic ratio is 10% while the accuracy is approximately 15%. Additional details of the XPS measurements are contained in the literature (24,25). 

Fig. 5.26 N Is XPS spectra for samples A-C with respective nitrogen doping levels [99].

Figure 4. C Is, 0 Is, and N Is XPS spectra of benzene-phthalimide (BPIM) on copper.

The complex nature of the bonding structure in transition metal nitrides incorporates a mixture of covalent, metallic and ionic components [126]. The nature on this bonding leads to high hardness, chemical inertness and, good electrical conductivity of these mixed nitride thin films. In what follows, we describe the surface chemical alteration of both a control and oxidized Ti—Al—N films (i.e., two different types of deposition room temperature (A) and liquid N2 temperature (B)), by measuring the chemical shifts in the Ti (2p), Al (2p), O (Is) and N (Is) XPS spectra. 

Fig. 11. High-resolution N Is XPS spectra for Ma-APTES2 from Table 2 (Durdureanu-Angheluta et al., 2011b). 

Fig. 16.23 N Is XP spectra of a Fe-PANI-C catalyst (a) before and (b) after a 500-h long-term stability test. The figure was taken from [189] reproduced by permission of ECS - The Electrochemical Society...

Fig. 23 High-resolution N Is XPS spectra, a BiCoPc/C, b hybrid BiCoPc/C-CoO, c hybrid BiCoPc/C-NiO. Reproduced with permission from Ref. [50]...

From nitrogen Is XPS spectra at 313 K because of the greater complexity of the N Is XPS spectra this value is considered as less reliable as the C Is value [149]. 

It was determined from the N Is photoelectron spectra that the form in which nitrogen was segregated is a surface nitride [33]. XPS studies of surface nitrides formed on Fe, Cr, Ni, Mo,... 

Figure Bl.25.2 shows the XPS spectra of two organoplatinum complexes which contain different amounts of chlorine. The spectrum shows the peaks of all elements expected from the compounds, the Pt 4f and 4d doublets (the 4f doublet is iimesolved due to the low energy resolution employed for broad energy range scans). Cl 2p and Cl 2s, N Is and C Is. Flowever, the C Is caimot be taken as characteristic for the complex only. All surfaces that have not been cleaned by sputtermg or oxidation in the XPS spectrometer contain carbon. The reason is that adsorbed hydrocarbons from the atmosphere give the optimum lowering of the surface free energy and hence, all surfaces are covered by hydrocarbon fragments [9].

One framework for discussing the bonding of metal complexes with diatomic ligands is to partition the complex conceptually into the units Mm+ and YJ". The values for m and n are determined by comparing the physical properties of the complex (Y—Y distance, v(Y—Y) (band position and intensity), electronic spectra, XP spectra, magnetic properties) with those of the isolated Y2" species. 

Main group element analysis was carried out with a Perkin-Elmer CHN elemental analyzer, while molybdenum analysis was performed using atomic absorption spectroscopy. The content of Mo and O on the surface of the catalysts was obtained by X-ray photoelectron spectroscopy (XPS) using a Shimazu ESCA-850 spectrometer with monochromatic MgKa. Since Mo 3p3/2 spectra overlapped with the N Is spectra for the nitrided catalysts, the degree of nitriding (N IsfMo 3d ratio) had to be obtained from a combination of elemental analysis and XPS. 

The XPS (N-ls) spectrum of the sample degassed at 973 K shows a large band of silazane species (58%), with minor shoulders of Si-NH2 (28%) and nitride (13%) species. The spectrum of the sample, deammoniated at 1123 K, shows a completely different picture. The dominant band in this spectrum is the nitride band (62%), with minor silazane (20%) and amine (18%) shoulders. Bands, attributable to Si-NH2—NH4C1 are not observable in the XPS spectra, suggesting that the actual concentration of these species is very small and not present on the actual surface (XPS is a typical surface probe, with a depth-profile of 0.3 - 3 nm, cfr. Appendix B). 

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