title: High-accuracy X-ray absorption spectra from mM solutions of nickel (II) complexes with multiple solutions using transmission XAS.
abstract: A new approach is introduced for determining X-ray absorption spectroscopy (XAS) spectra on absolute and relative scales using multiple solutions with different concentrations by the characterization and correction of experimental systematics. This hybrid technique is a development of standard X-ray absorption fine structure (XAFS) along the lines of the high-accuracy X-ray extended range technique (XERT) but with applicability to solutions, dilute systems and cold cell environments. This methodology has been applied to determining absolute XAS of bis(N-n-propyl-salicylaldiminato) nickel(II) and bis(N-i-propyl-salicylaldiminato) nickel(II) complexes with square planar and tetrahedral structures in 15 mM and 1.5 mM dilute solutions. It is demonstrated that transmission XAS from dilute systems can provide excellent X-ray absorption near-edge structure (XANES) and XAFS spectra, and that transmission measurements can provide accurate measurement of subtle differences including coordination geometries. For the first time, (transmission) XAS of the isomers have been determined from low-concentration solutions on an absolute scale with a 1-5% accuracy, and with relative precision of 0.1% to 0.2% in the active XANES and XAFS regions after inclusion of systematic corrections.
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chantler
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: M Tauhidul
authors.initials: MT
authors.lastname: Islam
authors.affiliation: School of Chemistry, University of Melbourne, Australia.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Best
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: Lachlan J
authors.initials: LJ
authors.lastname: Tantau
authors.affiliation: School of Physics, La Trobe University, Australia.
authors.forename: Chanh Q
authors.initials: CQ
authors.lastname: Tran
authors.affiliation: ANU College of Medicine, Biology and Environment, Australian National University, Australia.
authors.forename: Mun Hon
authors.initials: MH
authors.lastname: Cheah
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Payne
keywords: XAS with uncertainty; hybrid technique; nickel(II) complexes; transmission XAS