Dear Zhaomo Tian Yes, there’s a high likelihood that you have a strong self-absorption effect in your fluorescence-yield spectrum. Perhaps compare your spectrum to a Cu foil transmission spectrum as well. Pay attention particularly to the XANES distortions as you go over the ionisation threshold (edge step): features below the edge should have exaggerated amplitudes and features above the edge should have reduced amplitudes. The EXAFS amplitudes should be, at least in a first approximation, reduced by a constant factor, which is what your 1st shell fit seems to confirm. The pre-edge background probably curves upwards ‘too early’ as well, i.e., at lower photon energies compared the transmission spectrum. The strength of the self-absorption effect depends on the X-ray incidence angle relative to your Cu film plane and the angle at which your detector was placed: maximum self-absorption for grazing incidence/normal detection, minimum for normal incidence/grazing detection. Best wishes Sven -- Sven L.M. Schroeder ( mailto:s.schroeder@manchester.ac.uk mailto:s.schroeder@manchester.ac.uk) Professor of Applied Physical Chemistry School of Chemical Engineering and Analytical Science (CEAS) The University of Manchester, Manchester M13 9PL, United Kingdom http://www.slmslab.info/ http://www.slmslab.info Also at: School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom Tel +44 (161) 306 4502 Fax +44 (161) 306 8867 Office: Room C57 (Jackson's Mill) DISCLAIMER The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Zhaomo Tian Sent: 02 January 2013 05:58 To: ifeffit Subject: [Ifeffit] copper 1st shell coordination number Dear all, Thanks for your answer,Scott Calvin! I guess the value of sigma2 is normal, which is 0.0075. But your suggestion about the existing of modest degree of oxidation or other impurities is possible, I will think over it ^^ Actually this morning I improved this situation and got a reasonable CN value by trying self absorption correction to my data in Athena ( because I used fluorescence measurement). I think it is because the amplitude of my data increased after self absorption correction, so the CN of 1st shell also increased from around 8 to around12, which is more reasonable. So I really want to know if this self absorption correction really makes sense, or it might be just an accident?? Thanks a lot~ http://mail.postech.ac.kr/mail/PutAck.jsp?ack_args=c2VudF9maWxlPXpoYW9tbzE5ODlAcG9zdGVjaC5hYy5rci8uU2VudC8xMzU3MTA2MjgyMDY1Ljc1MzMucG9zdGVjaCZzZW5kX2RhdGU9MjAxMzAxMDIxNDU4MDImc3ViamVjdD1jb3BwZXIgMXN0IHNoZWxsIGNvb3JkaW5hdGlvbiBudW1iZXI=&to_email=ifeffit@millenia.cars.aps.anl.gov_____________________________________________________________________________________________________________________