C EXAFS

X-ray crystal structure data unless otherwise specified. b Differences between long and short Ni—N bonds. c EXAFS data. 

Alexeev, O., and Gates, B. C., EXAFS characterization of supported metal-complex and metal-cluster catalysts made from organometallic precursors, Top. CataL 10,273 (2000). 

Fig. 12.8. Passivation of iron by chromate and nitrite. Raw X-ray absorption data of (a) Fe and Fe304 and (b) Fe films after treatment (c) EXAFS data after Fourier transform (adapted from Ref. 31 with permission).

C. EXAFS (extended X-ray absorption fine structure) jointly developed with the CCLRC Daresbury Laboratory, U.K. (9), integrates the EXAFS analysis and refinement techniques of Daresbury s EXCURV92 software with Cerius s modeling tools, radically improving the ability to interpret the EXAFS data. 

Once the amorphous gel is heated, 170 NMR shows that both OZr3 and OZr4 environments remain, although there is an increase in line width. There is also an increase in the isotropic chemical shift of the peaks, especially the OZr4 peak, which moves from 303 to 321 ppm as the gel starts to crystallize. At the crystallization temperature (approximately 360°C), EXAFS results show that there is a distinct change in the structure, with the oxygen correlation now better fit by two closely spaced shells and a large increase in the coordination number to 12 associated with the Zr-Zr correlation. This is likely because the particles are nanocrystalline. 

Fig. 10.2. Experiniemal siH-up Ibr Iraiisniission (a) lluorL-sccncc (b) cnergy-Uispersive (c) EXAFS measurements (SY =. synchrotron radiation. 1,2.. = beam palh.s. M = monodironiator. In. I. 1 ionization chambers. D = detector (diode array). S scattering sample. P = sample. R = rel erence sample. B = slit. F = filter, SP — mirror).

Yan] Yang, D.S., Yoo, Y.G., Yu, S.C., Exafs Study on Nanocrystalline Fe4oCoioCu5o Alloy Processed by Mechanical Alloying , Nanostruci Mater, 12(5-8), 665-668 (1999) (Crys. Stmeture, Experimental, 5)... 

Rizzato A.P., Broussous L., Santilli C.V., PulcineUi S.H., Craievich A.F. Structure of SnOa alcosols and films prepared by sol-gel dip coating. J. Non-Cryst. Solids 2001 284 61-67 Schmutz C., Barboux P., Ribot F., Taulelle F., VerdaguerM., Fernandez-Lorenzo C. EXAFS, Raman and 31P NMR study of amorphous titanium phosphates. J. Non-Cryst. Solids 1994 170 250-262... 

Explanation of EXAFS and its evaluation for Ni metal, (a) absorption edge of Ni, (b) short-range order and coordination shells, (c) EXAFS function xW/ (d) Fourier transform of x FT to distance space. (From Rehr, J.J., Phys. Rev. Lett, 69,3397,1992.)... 

Two series of Pt/KL catalysts were synthesized by incipient wetness and vapor-phase impregnation (VPI) with a Pt(acac)2 complex [60]. The precalcined KL zeolite was physically mixed with the complex that had been sublimed up to 130 °C. To decompose the platinum precursor, the sample was heated in air at 350 °C. EXAFS and TEM showed that the VPI sample contains smaller particles than the catalyst prepared by incipient wetness, which are in close contact with the zeolite walls. This results in better diffusion of methylcyclopentane (no col-limation effect), better resistance to poisoning and coking, and a lower particle agglomeration rate. 

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