Efficient Determination of Optimal Regularization Parameter for Inverse Problem in EXAFS Spectroscopy

This paper presents a method for choosing the optimal regularization parameter in EXAFS analysis based on the L-curve-criterion without any external pa-rameter. The L-curve is a log-log plot of the norm of regularized solution ver-sus the norm of the corresponding residual norm. The optimal regularization parameter is chosen as a maximum of the L curve curvature. We apply this method in two experimental cases: crystalline Cu with well-known structure and aqua-ion Cm+3 with unknown structure. The optimal regularization pa-rameter leads to a stable solution with a good convergence of the iterative process