Surface chemistry of gold nanoparticles produced by pulsed laser ablation in liquids method is investigated by X-ray Photoelectron Spectroscopy (XPS). The presence of surface oxide expected on these systems is investigated using synchrotron radiation in conditions close to their original state in solvent, but free from substrate or solvent effects which could affect the interpretation of spectroscopic observations. For that purpose, we performed the experiment on a controlled free-standing nanoparticle beam produced by the combination of an atomizer and an aerodynamic lens system. These results are compared with those obtained by the standard situation of deposited nanoparticles on silicon substrate. An accurate analysis based on Bayesian statistics concludes that the existence of oxide in the free-standing conditions cannot be solely confirmed by the recorded core-level 4f spectra. If present, our data indicate an upper limit of 2.15 ± 0.68 % of oxide. However, a higher credence to the hypothesis of its existence is brought by the structureless valence profile of the free-standing beam. Moreover, the cross-comparison with the deposited nanoparticles case clearly evidences an important misleading substrate effect. Experiment with free-standing nanoparticles is then demonstrated to be the right way to further investigate oxidation states on Au-NP.

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Undoped and Ce-doped Lu3Al5O12 (LuAG) and Y3Al5O12 (YAG) single crystal fibers were grown by the micro-pulling down technique (µ-PD) with a purpose to fit the design of new dual-redaout calorimeter planned to operate in future experiences of high energy physics.Fibers up to 20 cm in length and 1mm in diameter were grown along [111] direction. Based on the measurements of the attenuation length along the fibers, the growth conditions to improve the fibers quality were selected. Our results showed that the grown fibers have the capability to be used for future detectors.