XAFS in the Tracking of Reactions in Aqueous Solution: a Case of Redox Reaction Between [AuCl4]– Complex Ions and Ethanol / Metoda XAFS W Badaniach Reakcji Zachodzących W Roztworach Wodnych: Przykład Reakcji Redoks Pomiędzy Jonami Kompleksowymi [AuCl4]- I Alkoholem Etylowym

Archives of Metallurgy and Materials

M. SIKORA¹  K. Pacławski² 

[1] AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, DEPARTMENT OF SOLID STATE PHYSICS, FACULTY OF PHYSICS AND APPLIED COMPUTER SCIENCE, 30-059 KRAKÓW, 30 MICKIEWICZAAV., POLAND;AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, LABORATORY OF PHYSICAL CHEMISTRY AND ELECTROCHEMISTRY, FACULTY OF NON-FERROUS METALS, 30-059 KRAKÓW,30 MICKIEWICZA AV., POLAND

关键词: Keywords: XAFS;    XANES;    redox reaction;    gold complex ions;    ethanol;   

DOI  :  10.2478/v10172-012-0113-5

学科分类：金属与冶金

来源: Akademia Gorniczo-Hutnicza im. Stanislawa Staszica / University of Mining and Metallurgy

【 摘 要 】

In this work the potential application of synchrotron radiation in the studies of reaction kinetics in aqueous phase were presented. After short introduction describing principles of technique and potential application of XAFS for the structural studies of reacting species, the experimental results of kinetic measurements of reaction between gold(III) chloride complex ions and ethanol were presented. Analyzing the changes of absorption intensity in the XANES spectra registered at Au-L3 edge during the reaction, the change of the valence state of Au central atom (form 3+to 0) of reacting complex ion was determined. Moreover, empirical XANES data gave the chance to register the kinetic curve and to determine the rate constant of the studied reaction. It was found that reaction is relatively slow (second-order rate constant k = 3.66 · 10-5 M-1s) and lead to the gold metallic phase formation in the system. Applying the continuous-flow method, within the first 600 ms of reaction the changes in XANES spectra were registered. From the obtained results, supported with numerical calculations, two intermediate forms of adducts appearing prior the electron transfer were suggested. It was concluded that when the classic methods, e.g. UV-Vis spectrophotometry, cannot be applied to studies of kinetics of reactions in aqueous solution, the XAFS technique can be a valuable and substitutive (or supplementary) tool for such measurements.

【 授权许可】

Unknown