EXAFS STUDY OF THE HYDRATION STRUCTURE OF GA3-SOLUTION - COMPARISON OF DATA FROM 2 LABORATORIES( AQUEOUS)

?he reliability of EXAFS data is a matter of controversy when new appl ications near the limit of the technique are carried out. Herewith we present results of aqueous solutions of Ga(NO3)(3) (0.005-1.0M) and Ga (CIO4)(3) (0.5M) measured at two synchrotron sources, SRS (Daresbury, UK) and SSRL (Stanford, USA), respectively, by two independent teams ( Sevilla, Spain and Uppsala-Stockholm, Sweden), and analyzed with two d ifferent software packages (XDAP and EXAFSPAK). For the first hydratio n sphere the fitting parameters obtained are the same (d(Ga-O-I)=1.95/-0.005 Angstrom, CN=6.0+/-0.1). Parameters apparently corresponding t o a second hydration sphere (d(Ga-O-II)=3.97+/-0.03 Angstrom CN=12+/-2 ) can be refined from both sets of spectra if the XDAP package is used , but no such contribution can be found with the EXAFSPAK program pack age. This is a consequence of different spline fitting techniques used in the two program packages.