X-ray spectroscopic and stroboscopic analysis of pulsed-laser ablation of Zn and its oxidation
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Pulsed laser ablation in liquids (PLAL) as an attractive process for ligand-free nanoparticle synthesis represents a multiscale problem to understand the mechanisms and achieve control. Atomic and nanoscale processes interacting with macroscale dynamics in the liquid demand for sensitive tools for in-situ and structural analysis. By adding X-ray methods, we enlarge the available information on millimeter-scale bubble formation down to atomic-scale nanoparticle reactions. X-ray spectroscopy (XAS) can resolve the chemical speciation of the ablated material during the ablation from a zinc wire target showing a first oxidation step from zinc to zinc oxide within some 10 min followed by a slower reaction to hydrozincite. X-ray imaging investigations also give additional information on the bubble dynamics as we demonstrate by comparing the microsecond radiography and optical stroboscopy. We show different features of the detachment of the ablation bubble from a free wire. The location of the first collapse occurs in front of the target. While a first rebound bubble possesses an homogeneous interior, the subsequent rebound consists merely of a cloud of microbubbles.
This work is supported by Deutsche Forschungsgemeinschaft under contrast BA 3580/15-1 and PL325/8-1 and through research within ”Matter, Materials to Life” of the Helmholtz Association. We wish to thank M. Zuber and T. Spangenberg for support during experiments at the synchrotron ANKA at KIT for provision of beamtime and M. Winterer for the access to the X-ray diffractometer.
Supplementary material 1 (AVI 26,750 kb)