Hi Mauro, On Tue, 11 May 2004 mauro@rulp.org wrote:
I'm dealing with the selfabsorption correction in Mo/Si multilayers with standing-wave-assisted EXAFS. In the fluorescence formula I have to multiply mu(E) for the thickness of the sample to obtain a pure number, so I need (cm^-1)*(cm).
Oh. You're original question did not mention self-absorption corrections at all. You asked about converting measured XAFS to mu in cm^-1. In general, this conversion (that is, to an absolute measure of absorption) is challenging for transmission data and essentially impossible for fluorescence data. But to do the self-absorption corrections on a well-characterized sample, you can use tabulated cross-sections (using barns/atoms is HIGHLY recommended over cm^2/gr or cm^-1 unless you have a pure compound: densities do not add!), and scale the XAFS wiggles to the edge jump of the absorbing atom. That assumes that the tabulated value for mu are correct except that they ignore the XAFS. I'm not sure I understand 'standing-wave-assisted EXAFS'. I'd interpret this to mean the measurements are done near the critical angle to control the penetration depth. Is that right? If so, and if you're asking for advice on self-absorption corrections, you'd need to give more details layer thickness, and measurement geometry. Hope that helps, --Matt