报告人：Prof. Augusto Marcelli
报告题目：Fabrication of Au, Pt, and AuPt Nanoparticle Arrays on Patterned Substrates by Pulsed Laser-induced Dewetting
Iron is the most abundant metallic element on the Earth, having a variable oxidation state that is extremely sensitive to the geochemical environment. Characterization of its valence state is therefore important in geology for defining the condition of formation of the rocks where the iron minerals under investigation are found. X-ray absorption spectroscopy (XAS) has been successfully applied to study Fe3+/Fe2+ ratio in a variety of geological materials also at micro-scale. The oxidation behaviour of a synthetic richterite, ideally K(NaCa)Mg5Si8O22(OH)2, has been investigated by using simultaneous XANES spectroscopy and X-ray diffraction. Combining these results with previous studies performed on similar samples by single-crystal structure refinement, M?ssbauer, Raman and High Temperature-Fourier Transform IR (HT-FTIR) spectroscopy it is possible to demonstrate that the structural evolution in Fe-amphiboles is a multi-step process. This research also demonstrates for the first time that the structural dynamics is driven by the oxidation of iron in the M1 sites and by the local structural strains induced by the distortions of iron sites in the chains of octahedra. A detailed understanding of this complex process may have significant implications in geophysics, providing an explanation to the observed high conductivity in some areas of the continental crust/mantle and in Material Sciences to design new materials with unique properties for technological applications.
Prof. Augusto Marcelli is a senior scientist at the Laboratori Nazionali di Frascati of the INFN, since 1984 he is involved in synchrotron radiation researches running in cooperation several scientific experiments in many facilities operational in the world such as Bessy, BSRF, Diamond, NSRL, PF, LURE, SSRL, SRS, UVSOR and ESRF. From 1997 to 2008 he was member of the International Scientific Committee of the X-Ray and Inner-Shell Conference Series and in 2002 he was co-Chair of the 19th International Conference of X-ray and Inner shell Process. He proposed and built in the DAΦNE-Light laboratory the first Italian Infrared synchrotron radiation beamline and was the scientist responsible for its operation till 2006. From 2005 to 2006 he was also responsible of the UV beamline at DAΦNE. He is one of the main proponents of the IKNO facility: a storage ring dedicated to the emission of coherent synchrotron radiation in the THz domain. In 2011, 2012 and 2014 he was a visiting professor at the University of Science and Technology of the Chinese Academy of Sciences. At present, he is one of the High-end Foreign Experts of SAFEA. His research areas include: correlation phenomena in X-ray absorption spectroscopy, multiple scattering theory applied to core level X-ray absorption spectra of solid and liquid systems, circular magnetic X-ray dichroism in intermetallics rare earth compounds, x-ray absorption in elements of geophysical interest and under extreme conditions, dust and aerosol characterization and ultra-trace detection, FTIR microspectroscopy and imaging applied to protein, cells and tissues, time resolved concurrent experiments and synchrotron radiation instrumentation, in particular IR and x-ray optics and fast infrared detectors.