Il mio essere un’insegnante di matematica e fisica delle scuole superiori (il mio primo anno scolastico come insegnante è stato il 1989/90) mi ha portata a questo dottorato e mi ha guidata nella mia ricerca: il bisogno di un rinnovamento, di una modifica delle strategie didattiche e dei contenuti è per me un’emergenza della scuola. Stiamo perdendo i nostri alunni alla scienza, quando loro stessi avrebbero la massima necessità del pensare scientifico nella società contemporanea, per essere cittadini a pieno titolo; per la mia generazione era sufficiente che solo una piccola frazione degli studenti si interessasse ed appassionasse alla conoscenza scientifica, ed i metodi didattici rispecchiavano questo approccio. Non possiamo più permettercelo. Mi sono quindi orientata alla creazione di strumenti innovativi che potessero essere effettivamente utilizzati dai miei colleghi, ma che potessero avere spazio anche fuori da contesti formali come la classe. Lo sviluppo della mia tesi rispecchia il percorso che ho seguito nei tre anni di dottorato, dalla comunicazione della scienza in generale agli strumenti da me progettati. Nel primo capitolo definisco sinteticamente l’evoluzione del concetto e significato di science communication, dal modello di deficit alla partecipazione informata del pubblico alle scelte di politica della scienza. La situazione attuale evidenzia molte ambivalenze: il pubblico valuta gli scienziati, non legati al mondo degli affari, come tra le persone di cui maggiormente ci si può fidare, per poi, invece, ritirare la fiducia in certi ambiti, quali la discussione sugli OGM. Per quanto la scienza sia reputata importante per la qualità della vita, le energie dedicate ad informarsi sono poche e le conoscenze risalgono spesso agli studi scolastici. Fanno eccezione i gruppi di interesse, che, motivati da una condizione particolare (la malattia propria o di un familiare, la preoccupazione per un impianto industriale, la vicinanza ad un possibile sito di discarica), acquisiscono per vie informali approfondite conoscenze in ambiti ristretti e si pongono come interlocutori degli scienziati. Per questo aspetto, l’avvento del web e la possibilità di avere informazioni gratuite praticamente su qualsiasi tema hanno modificato l’approccio alla scienza da parte di chi ne sia interessato. Anche le scelte politiche in merito alla comunicazione della scienza e le posizioni degli scienziati sono schizofreniche: per quanto venga politicamente riconosciuto che la comunicazione con il pubblico faccia parte dei doveri di uno scienziato, questa attività non viene incentivata dal punto di vista economico e non influisce nella progressione di carriera. Gli scienziati, poi, sono in netta maggioranza convinti dell’importanza del loro public engagement, ma lo sentono spesso come un furto di tempo ed energie al loro vero lavoro, la ricerca. Nel secondo capitolo presento una teoria dell’apprendimento, il costruttivismo, che è al momento quella che viene maggiormente applicata, con forti segnali di efficacia, nel superare le difficoltà ed i problemi posti dalla didattica tradizionale, quella delle lezioni frontali per capirci. Secondo il costruttivismo, il discente non è un recipiente vuoto che possiamo riempire con la conoscenza che proponiamo, ma possiede già una serie di rappresentazioni della realtà che ha maturato nel corso della vita ed in funzione delle sue esperienze. Possiamo quindi sperare di “insegnare” qualcosa solo se possiamo dimostrare che la nuova conoscenza che proponiamo è un modello della realtà più efficace in termini di rappresentazione e previsione di quella già formata. Inoltre, un vero cambiamento concettuale è possibile solo attraverso il diretto coinvolgimento del discente nella costruzione delle propria conoscenza, nel guidare il proprio apprendimento. La conoscenza viene quindi costruita personalmente dallo studente, se questo è convinto della significatività del nuovo apprendimento e se l’insegnante riesce a creare il giusto ambiente, dove il discente potrà costruire il proprio percorso cognitivo: il ruolo del docente cambia, si sposta dietro le quinte e, invece di fornire risposte, pone domande, le domande adatte a stimolare la curiosità ed a indicare la direzione lungo la quale proseguire la ricerca. Il terzo capitolo presenta una serie di esempi di didattica costruttivista delle scienze: dalla biologia, con l’impronta genetica, alle scienze della Terra con i terremoti, all’astrofisica con il Sistema Solare. Tutte le attività sono contraddistinte dal fatto di rendere lo studente regista del proprio apprendimento: i percorsi forniscono suggerimenti, pongono domande, ed è compito degli studenti, che lavorano in piccoli gruppi, trovare risposte che possano essere inquadrate in una cornice unitaria del fenomeno. Alcune proposte tengono conto dei vincoli che regolano l’andamento di una scuola reale: lezioni scandite ad orari fissi, risorse limitate, aule che non permettono l’interazione tra studenti e tra questi e il docente. Avvicinandomi alla scelta degli strumenti su cui avrei lavorato, ho deciso di sfruttare il fascino che l’astrofisica ha sul pubblico non esperto (ma anche esperto!): galassie, supernovae, universo, ammassi stellari, satelliti sono cool, soprattutto se supportati da una serie di bellissime immagini. Sotto questo aspetto l’astronomia è imbattibile. Una cernita dei materiali già disponibili mi ha portato a scegliere come tema per un primo strumento l’evoluzione stellare: infatti il Sistema Solare è per ora l’indiscusso protagonista del materiale didattico astronomico già disponibile ed ho ritenuto che spostare l’interesse verso le stelle ed il loro ciclo vitale potesse offrire nuovi spunti. Proporre una serie di lezioni, però, non avrebbe fatto altro che ripetere gli errori che stiamo commettendo in classe: abbiamo bisogno di rendere i nostri alunni protagonisti della costruzione della loro stessa conoscenza, coinvolgendoli il più attivamente possibile nel processo. Ed abbiamo bisogno di superare quella prima resistenza che quasi tutti, arrivati alle superiori, hanno ormai sviluppato verso le materie scientifiche. Nel quarto capitolo descrivo il primo strumento che ho progettato e che si trova, in forma stampata nella appendice n.1. Mi serviva un aggancio con la realtà quotidiana degli studenti, un qualcosa che fosse per loro familiare, ma che potesse diventare anche uno strumento per “fare scienza”, ed ho scelto la macchina fotografica digitale. Ho quindi costruito un percorso didattico, sotto forma di manuale di fotografia astronomica for dummies, che unisce attività pratiche, analisi di dati con software disponibile liberamente in rete e modelli fisici. Il punto di arrivo è la costruzione di un diagramma HR con dati raccolti dall’utente stesso, ma non è questo il tratto importante del manuale: conta soprattutto il percorso per arrivarci. Partendo dai fondamenti della fotografia, dei CCD che popolano le digitali, il manuale offre spunti su contenuti della fisica molto vari: dalle basi dell’ottica ai telescopi dell’ultima generazione dell’ESO ed ai satelliti per rilevare i fotoni altamente energetici, dal colore delle stelle alla spettroscopia delle regioni HII, passando per le stelle supermassicce e l’evoluzione stellare, chiamando in gioco sia temi che fanno parte del curricolo scolastico, che risultati delle ultime ricerche pubblicate. Il manuale, comunque, non va letto, ma piuttosto fatto: determinante è la scelta di partire dalle osservazioni e dalle foto fatte dall’utente per “scoprire” un fenomeno e solo dopo cercarne il modello che lo spiega. Un esempio: ad occhio nudo le stelle hanno colori diversi: perché? E come quantificare questa diversità? Una serie di foto di due stelle come Arcturus e Spica con la digitale attraverso tre filtri RGB (di plastica trasparente colorata) sono analizzate con un software per valutarne la luminosità nelle tre bande: perché Spica è più luminosa nel blu e meno nel rosso di Arcturus? Si tratta di un modo alternativo per presentare la radiazione di corpo nero. Questa strategia, che vede lo studente protagonista del proprio processo di apprendimento, attivamente coinvolto nelle attività, cognitivamente sfidato a trovare un modello esplicativo per un fenomeno da lui stesso osservato e che non trova soluzione nelle conoscenze già possedute, segue i dettami della didattica costruttivista. Ho formulato due proposte di percorsi didattici a partire dal temi affrontati nel manuale. Il manuale può essere utilizzato sia in un contesto formale, dove l’insegnante guida gli studenti attraverso i molteplici contenuti e li esorta ad approfondire alcuni temi, oppure dal singolo utente, motivato dalla curiosità e dalla voglia di capire. I materiali richiesti sono per scelta poco costosi ed i software suggeriti gratuiti in rete; la scrittura è volutamente informale e cerca di alleggerire contenuti a volte corposi senza perdere la correttezza scientifica. Mentre sviluppavo il manuale, ho lavorato alla creazione di un altro strumento, un gioco da tavolo, cui è dedicato il quinto capitolo. Una breve carrellata delle possibili definizioni di gioco precede un esame dello stato dell’arte dell’utilizzo dei giochi nella didattica della scienza. Sempre nell’ottica costruttivista, ho predisposto un gioco che stimolasse la curiosità ed il desiderio di “saperne di più” nel giocatore, che può essere chiunque dai dieci/dodici anni in poi. Considerazioni di carattere economico mi hanno fatto escludere un gioco a computer; la grafica ha infatti dei costi improponibili all’interno di una ricerca di dottorato. In ogni caso, sia sotto forma di videogiochi che simulazioni che giochi da tavolo, sono stati ancora realizzati ben pochi giochi per la didattica della fisica Con la collaborazione di uno studente al corso di laurea triennale di fisica presso la facoltà di Scienze di Trento, Matteo Conci, ho quindi progettato e realizzato un gioco da tavolo che simula la progettazione e realizzazione di una missione con equipaggio su Marte. Il tabellone di gioco è composto di due parti: una prima orbita interna di caselle che offrono varie opzioni per la composizione della missione, come lo scudo di protezione per le tempeste solari, il modulo in rotazione per simulare la gravità, diverse tipologie di motore e molto altro. La scelta è vincolata dai costi e dalla massa, come anche dagli imprevisti che possono accadere nel corso dell’orbita esterna, che rappresenta il viaggio vero e proprio: una micro meteorite, un incidente ad un membro dell’equipaggio, un guasto dell’impianto di riciclo possono essere superati solo se nella preparazione della missione si sono acquistate le opzioni necessarie. Una partita dura circa un’ora e per vincere è necessario realizzare per primi due esperimenti tra quelli che si hanno disponibili; il lancio dei dadi decide quali caselle vengono raggiunte. Manuale, regolamento e tabellone del gioco sono raccolti nella seconda appendice. Oltre al puro divertimento, il gioco, all’interno di una classe, stimola il desiderio di approfondire le questioni poste: che cos’è una tempesta solare e perché serve uno scudo? Perché le condizioni di microgravità protratte sono dannose alla salute? Come funziona un motore solare-elettrico? Le domande che possono nascere sono tantissime e dettate dall’interesse del giocatore, quindi significative per lui stesso; l’insegnante può allora sfruttare questa situazione e guidare gli studenti nella ricerca delle risposte alle domande che loro stessi si pongono, secondo una didattica costruttivista. Gli studi di NASA ed ESA per una missione su Marte hanno fornito la struttura della missione e i dati utilizzati. Il gioco è stato presentato all’European Science Open Forum (ESOF2010) che si è tenuto a Torino dal 2 al 7 luglio 2010; in questo contesto è stato possibile testarlo con varie tipologie di giocatori ed raccogliere informazioni per migliorarne la fruibilità. Nel sesto capitolo raccolgo le mie conclusioni, frutto anche del mio rientro in servizio come docente di scuola secondaria superiore; sono conclusioni in parte amare, che analizzano gli ostacoli che si trovano sul percorso di un rinnovamento della scuola italiana.

Cu2ZnSnS4 (CZTS) quaternary compound has attracted much attention in the last years as new abundant, low cost and non-toxic material, with desirable properties for thin film photovoltaic (PV) applications. In this work, CZTS thin films were grown using two different processes, based on vacuum deposition of precursors, followed by a heat treatment in sulphur atmosphere. The precursors were deposited using two different approaches: (i) electron-beam evaporation of multiple stacks made of ZnS, Sn and Cu and (ii) co-sputtering deposition of the three binary sulphides CuS, SnS and ZnS. All the materials were characterized both as isolated films and as absorber layer in solar cells, produced using the typical structure Mo/CZTS/CdS/i:Zno/AZO. Both growth processes were found to give good quality kesterite films, showing CZTS as the main phase, large grains and suitable properties for PV application, but higher homogeneity and stoichiometry control were achieved using the co-sputtering route. A detailed investigation on CZTS optical properties, microstructure, intrinsic defect density and their correlation with the material composition is presented. A strong effect of the tin content on the bandgap energy, sub-gap absorption coefficient, crystalline domain and grain size is shown and a model based on the increase of the intrinsic defect density induced by a reduced tin content is proposed. These studies suggested a correlation between the increase of the bandgap energy and the improvement of the material quality, which was also confirmed by the performances of the final devices. CZTS thin films were then assembled into the solar cells and their properties as absorber layer were optimized by varying both composition and thickness. CZTS samples produced from stacked evaporated precursors allowed achieving a maximum efficiency of 3.2%, but reproducibility limits of the evaporation process made difficult to obtain further and rapid efficiency improvements. The co-sputtering route was demonstrated to be a more successful strategy, assuring a fine-control of the film composition with good process reproducibility. A fast improvement of solar cell efficiency was obtained using this approach and a maximum efficiency of 5.7% was achieved. The relationship between the absorber layer stoichiometry and the device performances was investigated: the effect of the Zn enrichment and a possible influence of the Cu/Sn ratio on the device performances are discussed. Investigation on CZTS/CdS and CZTS/MoS2 interfaces revealed that the optimization of both buffer-layer and back-contact technology is a primary need for further improvement of CZTS solar cells.

The first and foremost goal of the present work was to develop novel theoretical and computational methods and use state-of-the-art techniques in electronic structure theory to interpret a specific set of physical problems mainly related, but not limited to, materials science. Our guiding principle was to relate information obtained from scattering experiments with the numerical solution of the multichannel dynamics of many-body systems, shedding light on the origin of electronic and optical properties of a variety of systems. The general approach adopted in this thesis was not to present separate chapters for theory, rather we introduced methods along with the experiments. In particular, we focused on the modeling of both ground and excited states of materials, on vibrational, core and valence electron spectroscopy of condensed matter systems using computational methods at different level of accuracy and complexity to interpret a number of experimental data. While these methods have been devised for this scope, their applicability, notably the treatment of the continuum states through multichannel scattering formalism, is totally general and can be applied to describe several different experiments, performed with a variety of apparently distant techniques. In particular, the Fano--Fesbach discrete-continuum interaction provides a common framework suitable to this task. Within this scheme, thus, the calculation of the spectral lineshapes measured by XPS, Auger, NEXAFS, and EEL spectroscopy can be reconciled on the same theoretical grounds with the investigation of the properties of ultra-cold Fermi gases at unitarity, or of the electronic capture and decay rate in ultra-hot plasma found in stellar environments or, finally, with the study of the epitaxial growth of nanostructured materials. Crossing the borders between several computational, theoretical and experimental techniques, this thesis should be of interest to a broad community, including those interested in aspects of atomic and molecular physics, electronic structure calculations, experimental and theoretical spectroscopy, astrophysics and scattering theorists in a broad sense.

Photovoltaic technology in the field of renewable energy has reached a high commercial interest over the past decade. The traditional silicon photovoltaic systems that is currently the most widespread, mainly due to government subsidies, have a low energy production. The wide use of material and the low efficiency of the silicon modules required the research and development of photovoltaic systems more efficient. The most promising technology is the photovoltaic concentration that increases the efficiency of the modules by reducing the area of the PV cell. The concentration photovoltaic has had considerable technological progress related to the development of multi-junction PV cells with high efficiency. Another approach is the technology of photovoltaic concentration with the spectral separation, so using the interference filters the solar spectrum is splitted into different optical bands. In this research was designed and built a CPV prototype system with spectral separation. The interference filters such as anti-reflection and dichroic mirror are made up of silicon dioxide and titanium dioxide. These oxides have been realized by means of physical vapor deposition reactive magnetron sputtering technique. The PVD technique allows to deposit thin films with a homogeneous process reproducible and reliable. In the first part of the work, the characterization of individual layers of oxide materials have allowed to extrapolate the optical constants. This is necessary for the design of the optical multilayer. The characterization has nvolved various analyzes such as atomic force microscopy (AFM) to determine the thickness and the roughness, compositional analysis Rutherforf backscattering spectrometry (RBS), and optical analysis UV-Vis-NIR. These analyzes were necesary to calibrate the deposition system in order to subsequently to realize the multilayer optics. The as deposited optical multilayers not confirm the optical design, and it was necessary to carry out an annealing at 350°C. In the second part of the work, there were also micro structural characterizations for evaluating the phase variation of the titanium dioxide with the annealing treatment. The Fourier transform infrared (FT-IR) analysis has checked the absorption peak of the Ti-O-Ti of the crystalline phase. In addition, X-ray diffraction (XRD) analysis verified the phase variation of titanium dioxide from purely amorphous phase with a slight presence of rutile to the anatase phase. Through the optical analysis it was possible to extrapolate the new optical constants corresponding to the phase of anatase. In the third part of the work, the ray tracing design of optical splitting of the CPV prototype was carry out. The CPV system is designed by coupling a concentration Fresnel a dichroic mirror. The focus of the radiation on the PV cell, is simulated by two ideal detector. The optical optimization as function of the f-number of the lens has allowed to define the layout for the prototyping phase. A further optimization is to insert a secondary optics element (SOE) of homogenization. The secondary optics will also limits the optical losses due to a misalignment of the CPV prototype. In the last part of this thesis is devoted to the preparation and the characterization of the CPV prototype. Were performed measures of solar radiation, which combined with the characteristic I-V-P curves of the solar cells have enable to evaluate the efficiency of the prototype system. The efficiency of the spectral separation system was compared with concentration multi-junction PV cells. Daily measurement were performed to compare the spectral separation technology than to the multi-junction technology. The results show that the separation system maintains a more constant performance during the day. Finally, thermal measurements were conducted on the component of the CPV prototype separation system. The experimental results allows to guarantee that the spectral separation is also a selective filter of temperature. This allows the solar cells to maximize the photovoltaic conversion and to reduce the overheating.

In this thesis work nanoscrystalline optical properties of diamond and two recent new NCD functionalisation techniques involving UV light (one step method and photochemical oxidation) have been investigated. Firstly the oxidation of diamond surface caused by the irradiation of the surface with UV-light in oxygen atmosphere was considered. Two different experiments in situ were realized in order to understand the physic-chemistry of this method. The chemical bonds between oxygen and surface carbon atoms were investigated by firstly performing an annealing treatment in ultra hight vacuum of a oxidized UV surface and then comparing the obtained result with annealing treatments of two different oxygenated diamond surfaces using other two techniques: plasma oxidation and piranha solution oxidation. An other interesting aspect on which clarity has to be made deal with amination process of diamond surface. As a first fundamental step, the efficiency on hydrogenated diamond surface was investigate. Successively the role of oxygen in the chemistry of amination process was studied performing in situ experiments using different terminated diamond surface (hydrogenated, chemically oxidized, UV oxidized) and different gaese (pure NH3 or NH3 + O2).

In this thesis I present two different research topics investigated during the course of my PhD, regarding the analysis of spatial structures in a Bose Einstein condensate. Ultracold atomic gases offer a privileged platform for such kind of experiments, thanks to the fine control that can be achieved on the system’s parameters and to the availability of advanced imaging schemes allowing for a great measurement accuracy. The first topic is about the shape of quantized vortices in an elongated condensate, with the goal of providing a quantitative analysis of the density structure of a quantized vortex filament hosted in a bulk 3D superfluid. We analyzed the shape of the vortex and studied its dynamics during a free expansion, or time of flight (TOF), of the hosting BEC, with the goal of making a quantitative comparison between theory and experiment for the structure of the core of a quantized vortex in three-dimensional (3D) condensates. Simultaneously imaging the sample along orthogonal directions after a long TOF allowed to map the complete 3D shape of the vortex at the end of the free flight, while the full expansion dynamics has been simulated with numerical solutions of the Gross-Pitaevskii equation. The same data analysis procedure has been applied to both the experimental images and to the density profiles computed with the simulations to ensure a faithful comparison. We were able to detail the evolution of the vortex parameters at all times combining a simple analytic scaling-law model valid at early times, experimental data for the width and the depth of the core at long expansion times, and the numerics that were used to bridge between the two. Additionally, we could check the validity of the predictions on the scaling of vortex parameters with the size of the BEC using the experimental data to interpolate between theoretical limiting models. We concluded that quantized vortex filaments can be optically imaged with standard techniques in 3D atomic BECs, at a level of accuracy which indeed is enough to show good quantitative agreement with the predictions of the GP theory for the width, depth, and overall shape of the vortex core. The second topic is a measurement of the equation of state of a single component BEC. The goal of this project is to verify the non-monotonic behaviour of the chemical potential of a homogeneous Bose gas of weakly interacting particles as a function of temperature, where one expects to find a maximum across the critical point of transition to the superfluid phase. This effect is believed to be a general feature of the normal-to-superfluid phase transition: it has been already experimentally demonstrated in unitary Fermi gases, and although the same is predicted to happen also in a gas of weakly interacting bosons, no experimental evidence has been reported so far. The measurement relies on the local density approximation, which allows to extract information about the thermodynamics of a homogeneous system from accurate measurements of the local properties of a trapped one. My work has focused on developing a series of imaging and data analysis techniques to measure the 3D density profile of a harmonically trapped gas, even in regimes of extreme density such as inside a Bose condensate. With a new high-dynamic-range method we were able to image the 3D density distribution of a trapped sample, leading to a low-noise measurement of the density distribution. We confirmed the existence of the non-monotonic behaviour of the chemicial potential across, and set the basis for further measurements of the thermodynamics of the system across the transition.In this thesis I present two different research topics investigated during the course of my PhD, regarding the analysis of spatial structures in a Bose Einstein condensate. Ultracold atomic gases offer a privileged platform for such kind of experiments, thanks to the fine control that can be achieved on the system’s parameters and to the availability of advanced imaging schemes allowing for a great measurement accuracy. The first topic is about the shape of quantized vortices in an elongated condensate, with the goal of providing a quantitative analysis of the density structure of a quantized vortex filament hosted in a bulk 3D superfluid. We analyzed the shape of the vortex and studied its dynamics during a free expansion, or time of flight (TOF), of the hosting BEC, with the goal of making a quantitative comparison between theory and experiment for the structure of the core of a quantized vortex in three-dimensional (3D) condensates. Simultaneously imaging the sample along orthogonal directions after a long TOF allowed to map the complete 3D shape of the vortex at the end of the free flight, while the full expansion dynamics has been simulated with numerical solutions of the Gross-Pitaevskii equation. The same data analysis procedure has been applied to both the experimental images and to the density profiles computed with the simulations to ensure a faithful comparison. We were able to detail the evolution of the vortex parameters at all times combining a simple analytic scaling-law model valid at early times, experimental data for the width and the depth of the core at long expansion times, and the numerics that were used to bridge between the two. Additionally, we could check the validity of the predictions on the scaling of vortex parameters with the size of the BEC using the experimental data to interpolate between theoretical limiting models. We concluded that quantized vortex filaments can be optically imaged with standard techniques in 3D atomic BECs, at a level of accuracy which indeed is enough to show good quantitative agreement with the predictions of the GP theory for the width, depth, and overall shape of the vortex core. The second topic is a measurement of the equation of state of a single component BEC. The goal of this project is to verify the non-monotonic behaviour of the chemical potential of a homogeneous Bose gas of weakly interacting particles as a function of temperature, where one expects to find a maximum across the critical point of transition to the superfluid phase. This effect is believed to be a general feature of the normal-to-superfluid phase transition: it has been already experimentally demonstrated in unitary Fermi gases, and although the same is predicted to happen also in a gas of weakly interacting bosons, no experimental evidence has been reported so far. The measurement relies on the local density approximation, which allows to extract information about the thermodynamics of a homogeneous system from accurate measurements of the local properties of a trapped one. My work has focused on developing a series of imaging and data analysis techniques to measure the 3D density profile of a harmonically trapped gas, even in regimes of extreme density such as inside a Bose condensate. With a new high-dynamic-range method we were able to image the 3D density distribution of a trapped sample, leading to a low-noise measurement of the density distribution. We confirmed the existence of the non-monotonic behaviour of the chemicial potential across, and set the basis for further measurements of the thermodynamics of the system across the transition.

The present work is conducted in the field of few-body methods and it concerns the extension of the Non-Symmetrized Hyperspherical Harmonics method in order to treat quantum systems with different species of particles and additional degrees of freedom, like particle mixing. The aim is to introduce it as a new tool in the ab-initio study of light hypernuclei, and, more in general, of few-body quantum systems composed by a variety of different objects. To this end precise benchmark results for light hypernuclei with A=3-5 are provided and the perspectives of applications to systems with A>5 and the employment of the most recent hypernuclear interactions are discussed.

Weather and climate are topical issues widely present in the media, in the public culture, in political and socio-economic agendas and also in school guidelines. Having said that, confusion and a lot of misconceptions still exist with regards to issues such as climate change, greenhouse gases and the greenhouse effect, pollution, anthropogenic emissions, ozone hole, predictability of weather and climate, stationary processes, radiation fluxes and balances in the Earth system etc. These themes are poorly addressed in the actual teaching practice in secondary schools, particularly from a quantitative point of view involving the underlying laws of physics, which are necessary for the understanding and construction of correct conceptual models of phenomena. Teachers often do not feel comfortable or lack the specific background for addressing such themes quantitatively, claiming for training initiatives which happen unfortunately only as a result of sporadic and local initiatives. For historical reasons, typical of the Italian context, these themes are usually addressed in subjects like geography or natural sciences for what concerns education in formal contexts such as primary and secondary schools and universities, but their treatment and significance would greatly benefit from an interdisciplinary approach, involving also the quantitative experimental approach of physics. At the same time, teaching physics from its general principles to their application in the context of weather phenomena and climate system, would improve the engagement and interest of students, fostering cooperation among teachers of different subjects, bridging boundaries and approaches characteristic of single disciplines. This would promote an integrated view of science as the result of a process, based on the application of the scientific method to the investigation and modeling of phenomena, where also technological advancement plays an important role, rather than as a mere collection of results and knowledge. In this perspective the present work develops from the research in atmospheric physics, performed by the candidate during one year at Concordia station, Antarctica, presenting on one hand a series of physics communication initiatives designed and tested with innovative formats such as TEDx conferences, videoconferences with researchers working on the field, social platforms and traditional media, targeted to different audiences. On the other hand it presents the proposal of a teaching learning sequence based on quantitative experimental activities, demonstrations and simulations, targeted to secondary school students and pre-service teachers, integrating general physics with its applications to the atmosphere and to the climate system. The teaching learning sequence has been experimented with graduate students of the course: ''Experimental physics laboratory at high school I'', held at the Department of Physics of the University of Trento and in collaboration with IPRASE, it has been proposed in the form of a training course for physics and chemistry teachers and their technical assistants as a framework for the integration of physics and chemistry. The results of pre and post tests used as an evaluation tool of this preliminary experimentation will be presented, encouraging future developments of the sequence and further diffusion of weather and climate issues in the teaching practice through capillary pre-teachers' and teachers' training initiatives.

This thesis proposes to provide a unified and systematic strategy to overcome the second timescale in protein folding, by exploiting qualities and drawbacks of the Bias Functional Method and proposing new theoretical approaches to overcome its limitations. The first half of the thesis is dedicated to the development of theoretical solutions to the dependence of the Bias Functional Method on an a-priori defined collective coordinate and microscopic non-reversibility of the dynamics. The second part of the manuscript is devoted to applications of the BF method on two different proteins: Canine milk lysozyme and alpha1-antitrypsin (A1AT).

Nanodiamonds (NDs) are the subject of intense investigation for their unique physical and chemical properties. Due to high hardness, optical transparency and biocompatibility, NDs find applications in tribology, catalysis and drug delivery. When enriched with nitrogen-vacancy (NV) centers, NDs can be used in bioimaging and biosensing. While the field is progressing rapidly, a number of problems are still open. In this dissertation I have tackled two important aspects for the development of NDs as biosensors: 1) production of NDs with controlled size and properties; 2) characterization and optimization of commercial fluorescent NDs as probes of paramagnetic species. In the first part of my thesis, I report a novel synthesis route for NDs by pulsed laser ablation (PLA) in water. PLA can directly produce diamonds on a nanoscopic scale, with potential advantages over alternative methods, like grinding of bulk crystals or detonation techniques. Specifically, I demonstrate synthesis of nanometric diamond crystals by PLA in an aqueous environment and investigate the thermodynamics of this process. Indeed, the synthesis of NDs by PLA is related to a drastic change in the thermodynamic state of the target upon laser irradiation. Fast laser-induced heating results in melting and superheating of the target, followed by a strong boiling, a process named “phase explosion†, and then by a fast cooling of the molten material in water. I provide a theoretical description of both superheated and undercooled liquids and of the mechanism of phase explosion. The investigation of the link between the metastable liquids (superheated or undercooled) and the synthesis of nanoparticles is carried out by theoretical analyses, computer simulations and comparison of our experimental data with previous literature. In the second part of the thesis I turn to commercial NDs enriched with (NV) centers. The purpose of the investigation is to explore the use of fluorescent NDs for sensing of paramagnetic species of biological interest. To this end, I explored the effects of size and surface coating on the optical properties and sensing capabilities of fluorescent NDs. Following a theoretical introduction to the basic properties of the NV centers and to the ground state spin dynamics of these color centers, I describe the set up used for the experimental characterization of the NDs. All NDs used in my experiments, characterized by different sizes and coatings, presented high fluorescence levels, the result of a relatively high concentration of NV center. In all NDs, I observed a fast loss in coherence due to interactions between the NV centers and with the external environment. The most striking and unexpected result concerns the dynamics of the spin-lattice relaxation time T1. Differently from previous reports, spin dynamics after polarization of NV centers could not be described by a single exponential decay, but showed a sharp signal increase that I attribute to charge dynamics and charge conversion between the negative and neutral forms of the NV center. Unexpectedly, I found that coupled charge and spin dynamics are strongly affected by paramagnetic interactions, yielding unprecedented sensitivity to subnanomolar concentrations of gadolinium, a strong paramagnetic contrast agent. The connection between relaxation dynamics and concentration of paramagnetic species can open new perspectives in biosensing and in bioimaging. As a demonstration of a practical application, I tested the sensitivity of NDs in the detection of deoxyhemoglobin, an endogenous paramagnetic species in blood.