New opportunities in XAFS investigation in the 1–2 keV region

Characterization of Local Chemistry and Disorder in Synthetic and Natural α-Al2O3Materials by X-ray Absorption Near-Edge Structure Spectroscopy

“…Comparison of our -Al 2 O 3 experimental spectrum with those presented by other authors (Brytov et al, 1979;Wong et al, 1994;Ildefonse et al, 1994;Li et al, 1995Li et al, , 1996Cabaret et al, 1996;Kinoshita et al, 1997; note, however, that not all state whether their sample was natural or synthetic) is satisfactory. Indeed our spectra appear to be the best resolved and most intense of all; therefore, they allow a more accurate evaluation and a deeper discussion than previously possible.…”

“…Further wide, weak and yet evident undulations extend to the EXAFS region (not shown; cf. Wong et al, 1994). The energies of the K-edge features do not change when quartz is used instead of YB 66 (cf.…”

“…In other aluminosilicates, the Al K edge is well known to undergo a signi®cant negative shift (2.2±5.2 eV) when the Al coordination number is lowered from six to four (McKeown et al, 1985;Wong et al, 1994;Li et al, 1995;Cabaret et al, 1996;Wu et al, 1997;Mottana et al, 1997). In Fig.…”

“…As an additional calibration, we aligned all of them using the 1594 eV glitch detected as intrinsic in our YB 66 crystal (cf. Wong et al, 1994). The energy value of each feature was then measured by ®tting a Lorentzian line, with errors always well below 0.1 eV within each spectrum and with 2' 9 0.1 eV among different spectra.…”

“…Theoretical and experimental studies on Al 2 O 3 are numerous and involve a variety of methods (Tossel, 1975;Balzarotti & Bianconi, 1976;Brytov et al, 1979;Batra, 1981;Ciraci & Batra, 1983;Causa' et al, 1987;McKeown, 1989;Kirfel & Eichhorn, 1990;Blonski & Garofalini, 1993;Wong et al, 1994;Ildefonse et al, 1994;Li et al, 1995Li et al, , 1996Cabaret et al, 1996). Most previous experimental studies were performed on only one, usually synthetic, sample.…”