Edward: For rhenium the examples published in the literature use the first inflection point to define the oxidation state. Indeed for a set of rhenium oxides of formal oxidation state 4, 6 and 7 there is close to a linear relationship of formal oxidation state with edge position. We have collected such data several times. Regarding your other point about the white line intensity of rhenium nanoparticles, this has been the subject of some recent research of ours. We are close to submitting a manuscript where we discuss this point for rhenium supported on alumina. We also observe the same phenomena that you describe: even though the rhenium is formally reduced, the white line intensity is substantially more intense that the equivalent metal reference. Until this manuscript is ready I refer you to an older publication: J. Phys. Chem. 95 (1991) 225-234 by Fung et al. where they also note the same. We have also done some FEFF8 XANES calculations of small Re clusters and there is a clear trend of increasing white line intensity with decreasing cluster size. I would be willing to share our rhenium reference spectra if you contact me directly. Simon R. Bare Senior R&D Associate UOP LLC 25 East Algonquin Road Des Plaines, IL 60017-5017 Phone - 847.391.3171 Cell - 630.842.6890 Fax - 847.391.3719 simon.bare@uop.com www.uop.com -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Edward L. Kunkes Sent: Thursday, May 17, 2007 10:29 AM To: ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] white line intensity v. edge position in determining oxidation state of Re Hi everyone, I am trying to determine the oxidation state of Re in PtRe nanoparticles catalysts supported on carbon. The ReLIII edge was measured before and after an in-situ reduction in hydrogen. Can anyone suggest Which characteristic of the edge is more related to oxidation state ? Is it the integrated white-line intensity or the position of the edge(point of maximum derivative). The edge position of the ReLIII edge of my particles is the same as that of Re foil, however the white line instensity is significanty higher. For the non-reduced PtRe particles, the edge position is similar to that of ReO2 (with a larger white line intensity). Also, does anyone have any Data on Re-foil, HReO4 and ReO2 so that i can compare it to the data i measured for my standards ? Thank you very much for your help -Edward Kunkes _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit