Quantitative mapping of species moving in solution by x-ray projection microscopy

An x-ray projection microscope equipped with a digital camera allows a rapid and independent mapping of copper and iron ions in an aqueous sulphate solution during the corrosion/deposition process of a metallic iron electrode in a copper sulphate solution. The concentration distributions of the two species can be quantified from a pair of x-ray images acquired in 20 s with a resolution on the order of 10 mu m. Four pairs of images have been acquired each minute of the corrosion deposition process. This technique makes it possible to follow the concentration distribution of the two species as a function of the space (x,y) and time coordinates with a detection limit in the 10 ppm range. (C) 1997 American Institute of Physics.