Evidence of four-body contributions in the EXAFS spectrum of Na2Co[Fe(CN)(6)]

This contribution deals with an EXAFS investigation of Na2Co[Fe(C)(6)] at the K-edges of both Fe and Co. Na2Co[Fe(CN)(6)], a well known and easily prepared mixed hexacyanoferrate, is characterised by a unit cell containing linear ''Fe-C-N-Co'' chains where a super-focusing effect may be observed at the K-edge of both transition metals. The multiple scattering (MS) signal intensity associated with the linear chain (four body contribution) is comparable with the first shell contributions. The combined fit over two edges, the intensity of the MS signal and the large number of experimental points included in the fit, permit an accurate extraction of the structural parameters at the limit of the EXAFS sensitivity. (C) 1997 Elsevier Science B.V.