XANES spectra

That observed for TS-1 is not peculiar for TS-1 only and can be observed on other titanosilicates like Ti-MSA, a mesoporous amorphous material that has Ti(Vl) centers exposed on the surface of the pores [124,125]. In this case, easier experiments could be performed by Prestipino et al. [50] as the peroxo/hydroperoxo complexes can be formed by dosing f-butyl hydroperoxide (which does not enter the 10-membered rings of TS-1). The XANES spectrum of Ti-MSA in vacuum is typical for almost r -like Ti(IV) centers (the intensity of the Ai T2 pre-edge peak being only 0.69, as compared with 0.91 for TS-1). Upon dosing the t-butyl hydroperoxide in decane solution on Ti-MSA, a spectrum similar to that obtained on TS-1 contacted with anhydrous H2O2 is observed on both XANES and EXAFS regions [50]. When the... 

Figure 2 shows a representative XANES spectrum from a bulk gold sample (a 1 pm gold film) and a representative spectrum of gold reacted with oat biomass. 

Fig. 20 As L -edge XANES spectrum for CrAs, measured in fluorescence mode. Reprinted with permission from [61]. Copyright Elsevier...

Fig. 5. XANES spectrum of a typical TS-1 sample in vacuum. Inset intensity of the pre-edge peak (spectra normalized to the edge jump) for samples with various Ti contents. Because the height of the edge jump is proportional to the Ti content, the intensity of the normalized pre-edge is invariant (within experimental uncertainty) with Ti concentration [Reprinted from Ricchiardi et al (41) with permission. Copyright (2001) American Chemical Society].

Figure 2. XANES of Rasa Coal Top XANES spectrum Bottom 3rd Derivative of XANES spectrum.

Figure 2. Effect of coordination geometry on V XANES spectrum V naphthenate (----), (---). ...

Figure 5. Effect of V source on V XANES spectrum of Catalyst A...

Figure 7. Comparison of V XANES spectrum of bulk VgOg (----) with...

Figure 8. Effect of steaming temperature on V XANES spectrum of...

Figure 9. Effect of steam treatment on V XANES spectrum of Catalyst B containing 5000 ppm V (from V 0 ) 1450 F steaming (---), 1450 F air calcination (---).

Thus we can directly deduce the XANES spectrum of the product state from the measured transient signal and the reactant state XAS, if we knowXO Alternatively, we can derive fit), if we know the exact shape of the product state XAS, P(E,t). The details are given in ref. 14. The resulting spectrum for the [Ruln(bpy )(bpy)2]2+ species is shown in Fig. 4a (trace P). It contains an energetic shift of all features by 1.2 eV, together with the photoinduced appearance of the A feature, as expected. The A-B splitting (4 eV) and the B /A intensity ratio (ca. 2.3) is indeed close to the values observed for [Ru"(NH3)6]3+ complex [18,20], which has the same valency and a similar coordination symmetry (Oh versus D3) as the bipyridine complex. 

X-ray absorption near edge structure (XANES) spectrum An analysis from X-ray absorption spectroscopy (XAS) and, in particular, X-ray absorption fine structure (XAFS) spectroscopy. XANES can be used to identify the valence state of arsenic in solid samples (Teixeira and Ciminelli, 2005 Kober et al., 2005). 

Despite the overall similarity between the XANES spectrum of the mixed model compounds and the asphaltene and coal samples, there are some significant differences in the relative energies of the various features. One possible explanation for these differences is that subtle electronic differences at the sulfur are reflected in the sulfur XANES. Such differences might be expected to arise from extended ring structures or from substituents. This will be a subject for further study. 

Table 4.4. The tribochemical effect of micellar additives (calcium sulfonate, calcium phenate) + ZDDP (1.2 wt%) on the polyphosphate chain length from XANES spectrum measured in the bulk FY technique and in surface TEY technique (Yin et al., 1997b)...

---