Download or read book Spectroscopie d absorption X et dichro sme circulaire magn tique written by Guillaume Champion and published by . This book was released on 2003 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Magnetism is a recent pluridisciplinary field of research on various topics. We show, in this thesis, how X-ray Absorption Spectroscopy (XAS), X-ray Magnetic Circular Dichroism (XMCD) and their theoretical tools give information on the electronic and magnetic structures of spin carrier ions in systems representative of the new trends in this domain. For the first time, XMCD has enabled to characterize the nature of the exchange interaction in photomagnetic cobalt-iron Prussian blue analogs. Beside, we have quantified by XAS, coupled with multiplet calculations, the Co(II) cations crystal field in these systems, which governs the magnetic properties, and studied its evolution during the irradiation. These studies led us to propose an hypothesis on the structural evolution that comes with the light induced electron transfer. We have developed a new approach through the coupling between experiment and multiplet calculations giving access to the spin density in molecular systems. We illustrate this point on the example of clusters of Mn(II) and Cu(II) cations antiferromagnetically coupled and presenting a quantic effect of local magnetization loss. A first remnant XMCD signal was obtained in molecular-based magnets. This works is the first step in the study of the origins of remanence in single molecule magnets presenting original magnetic properties such as Mn(12). Finally, using the orbital selectivity of XMCD, we probed the different exchange interaction pathways responsible for the spin frustration phenomenon observed in Gd(III) and organic radicals alternating one-dimensional chains.
Download or read book Dictionnaire des termes de m decine written by Henry Eugène de Méric and published by . This book was released on 1899 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
