Hi Darren, On Thu, Jun 27, 2013 at 8:48 AM, Darren Dale wrote:

Hello All,

If I have a Ta(1-x)Ge(x)O(y) thin film, with Germanium concentration of a few percent, is it possible in principle to get useable fluorescence-mode EXAFS spectra around the Ge K edge (11.1 keV)? Or is it likely that the spectra would be complicated by additional Ge fluorescence excited by processes triggered by Tantalum L edge absorption (9.88, 11.13, 11.68 keV)?

Thanks, Darren

Ack -- I think the Ta L2 edge (33 eV above Ge K edge) is going to make that very hard. You might be able to isolate Ge Kalpha from the Ta L lines with a crystal analyzer, but the change in penetration depth at the Ta L2 edge is going be huge, unless the film is much much less than an absorption length. --Matt

Darren, You will see the Ge K-edge rising just before the rise of Ta L2 edge. In principle, if you collect good quality data around Ta L2 edge (that is, from ~ 150 eV below and up to 500 eV above (because Ta L3 edge will come up after that)), you may be able to isolate the Ge K-edge peak from Ta L2 pre-edge. But, of course, it will be only the region in the immediate vicinity of Ge 1s-4p transition peak, not post-edge. Still, you may be able to tell between oxidized and reduced Ge based on the peak shape, as they are very different between these two states. I doubt you can do much more than that. And, of course, no EXAFS. For such separation you will need to approximate Ta L2 edge using a combination of arctan and Lorentzian curves (please see the literature for different methods for such fits). You will be lucky if Ta L2 pre-edge is smooth and can be fit analytically (I haven't done it and it will not work if it has any pre-edge peaks). Anatoly ________________________________________ From: ifeffit-bounces@millenia.cars.aps.anl.gov [ifeffit-bounces@millenia.cars.aps.anl.gov] on behalf of Darren Dale [dsdale24@gmail.com] Sent: Thursday, June 27, 2013 9:48 AM To: ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] Basic EXAFS question Hello All, If I have a Ta(1-x)Ge(x)O(y) thin film, with Germanium concentration of a few percent, is it possible in principle to get useable fluorescence-mode EXAFS spectra around the Ge K edge (11.1 keV)? Or is it likely that the spectra would be complicated by additional Ge fluorescence excited by processes triggered by Tantalum L edge absorption (9.88, 11.13, 11.68 keV)? Thanks, Darren _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit