Estimation of the experimental standard deviations in EXAFS measurements

We have studied the multiple recording method to estimate if it possible to obtain by this way reliable EXAFS data standard deviations. The examinatio n of more than 10 different samples, each of them recorded at least 8 times , gave us the possibility to show that the partial standard deviations foll ow the expected probability laws. Even when the number of samples is small, it is possible to give a reasonable upper limit of epsilon which could be used as the statistical contribution of the experimental error bars. In som e cases we have found that a uniform weighting by 1/epsilon(2) may fail to give a good fit, especially in the high part of k space. We present a simpl e method of weighting which lead to more satisfying fits without loosing th e correct normalisation of the fined Delta chi(2) necessary to obtain corre ct fitted parameters error bars.