Progress in x-ray spectroscopies for the study of advanced materials

This thesis work is focused on the use of selected core-level x-ray spectroscopies to study semiconductor materials of great technological interest and on the development of a new implementation of appearance potential spectroscopy. Core-level spectroscopies can be exploited to study these materials with a local approach since they are sensitive to the electronic structure localized on a chemical species present in the sample examined. This approach, in fact, provides important micro-structural information that is difficult to obtain with techniques sensitive to the average properties of materials. In this thesis work we present a novel approach to the study of semiconductors with core-level spectroscopies based on an original analysis procedure that leads to an insightful understanding of the correlation between the local micro-structure and the spectral features observed. In particular, we studied the micro-structure of Hydrogen induced defects in nitride semiconductors, since the analysed materials show substantial variations of optical and electronic properties as a consequence of H incorporation. Finally, we present a novel implementation of soft x-ray appearance potential spectroscopy, a core-level spectroscopy that uses electrons as a source of excitation and has the great advantage of being an in-house technique. The original set-up illustrated was designed to reach a high signal-to-noise ratio for the acquisition of good quality spectra that can then be analyzed in the framework of the real space full multiple scattering theory. This technique has never been coupled with this analysis approach and therefore our work unite a novel implementation with an original data analysis method, enlarging the field of application of this technique.

Benvenuto Rambaldi da Imola: dantista in progress

Si procede ad un’analisi diacronica delle tre redazioni del commento dantesco di Benvenuto da Imola (dalle "recollectae" bolognesi e ferraresi al "Comentum"), considerando il testo benvenutiano quale «opera umana o lavoro in fieri», di cui rappresentare «drammaticamente la vita dialettica», così come il Contini iniziava a fare, negli anni ’30, con gli ʻscartafacciʼ ariosteschi. Secondo tale impostazione, si prende in esame la multiforme attitudine pedagogica di Benvenuto, di cui si indica, con riferimento ad altri commentatori coevi, danteschi e non, il contesto operativo. Nella seconda parte si ricostruisce, in senso sempre diacronico, la problematica oscillazione del commentatore tra tendenze avanguardistiche in direzione umanistico-petrarchesca e strenua apologia del testo dantesco. Nella terza ed ultima parte sono vagliate le originali idee benvenutiane riguardo alla lingua e alla poesia della Commedia, delle quali si ripercorre, attraverso l’esame delle varianti redazionali, la progressiva messa a fuoco. Obiettivo dell’elaborato, insomma, è restituire una descrizione organica e problematica della ricerca dantesca, "in progress", portata avanti da Benvenuto da Imola.