Chemical state plots

Figure 5. Auger chemical state plot for aluminum compounds as obtained using silicon Ka x-radiation.

Auger chemical state plot, V5f chemical state data, V5t X-ray photoelectron spectra,... 

Fig. 2. Chromium chemical state plot for chromium oxide and fluoride samples before and after activation with halocarbons (static charge reference C Is 284.8 eV) (reproduced with permission from J. Catal., 159 (1996) 270 (39]).

In the chemical state plot of fluorine, only one species has been found for y-alumina activated by CHF3 (cf Fig. 6), and chemical states of fluorine in this material and in /J-A1F3 appear to be very similar. Exposure to air of the material leads to hydrolysis. The chemical state plots of fluorine, indicate that hydrolysis of A1—F surface bonds commences after 10 min and continues over a period of at least one month. 

Fig. 5. Chemical state plot for Al in CHF3 activated -alumina (circles give uncertainties of measurements). BE and KE data are referenced to Au 4f7/2 (84.0eV). (a) majority species (b) minority species [71],...

Figure 6. Applications of the chemical state plot to unknown copper samples. Duplicate points for certain chemical states represent data from different sources...

Figure 10. Chemical state plot for oxygen in oxides and hydroxides ( i i). Numbers represent the number of compounds included in the area.

Figure II. Chemical state plot for oxygen in carbon-oxygen compounds (33) ((O) carbonyl (carboxylate ( ) carbonate)...

Wagner has also developed a two-dimensional chemical state plot (24-25) that makes use of the Auger parameter to distinguish between compounds of an element that have the same, or nearly the same, binding energy. In cases where the XPS chemical shift alone is not enough to determine the chemical state, these plots or the Auger parameter by itself can be used to help identify the type of compounds present In the surface. 

BY FINGERPRINTING AND REFERENCE TO DATABASES OR TO CHEMICAL-STATE PLOTS... 

Activation in CH3-COIF2 at 525 K again resulted in. single Al and and F species combined to form an amorphous Al hydroxyfluoride phase undetectable by XRD analysis. Only this activation procedure provided the full catalytic activity obtained with p-AlFr, the reference catalyst." which correlates well with the fact that y-alumina activated in CH3-CCIF2 at 525K can be seen to occupy positions on the two chemical-state plots very close to those of p-AlFv... 

Figure 7a,b Al (a) and F (b) chemical state plots for y-alumina activated for catalyzed halogen exchange reactions, with CHClFi and CH3-CCIF2 at different temperatures. Data recorded from reference samples (P-AIF3, AI(OH)Fi, AIF2,3(OH)o,7 H1O and AI(OH)3) are included for comparison. (Redrawn from Ref. 32.)... 

C. D. Wagner and D. M. Bickham, NIST Standard Reference Data Base 20 NIST X-ray Photoelectron Spectroscopy Database Version l.O, National Institute of Standards and Technology, Gaithersburg, MD, 1989, (Version 2.0 was announced to cover also chemical-state plots for many elements in J. R. Rumble, D. M. Bickham and C. J. Powell, Surf. Interface Anal. 19, 241 (1992).)... 

Figure 1.26 Chemical state plots for F Is and Mg Is orbitals of chromium(lll)-doped Mgp2 prepared from CrOs (CrO), CrClj (CrCI) or Cr-acetat (CrAc) in different concentrations (Reprinted with permission from [54] Copyright (2005) Elsevier Ltd.)...

FIGURE11 Wagner chemical state plot for arsenic. The modified Auger parameter is evaluated on the diagonal grid. [From Wagner, C. D., etal. (1979). Handbook of XPS, Perkin Elmer Corp, Eden Prairie. MN.]... 

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