The pulsed jet Fourier transform microwave spectroscopy have been applied to several molecular complexes involving H2O, freons, methane, carboxylic acids, and rare gas. The obtained results showcase the suitability of this technique for studying the intermolecular interactions. The rotational spectra of three water adducts of halogenated organic molecules, i.e. chlorotrifluoroethylene, isoflurane and alfa,alfa,alfa,-trifluoroanisole, have been investigated. It has been found that, the halogenation of the partner molecules definitely changes the way in which water will link to the partner molecule. Quadrupole hyperfine structures and/or the tunneling splittings have been observed in the rotational spectra of difluoromethane-dichloromethane, chlorotrifluorometane-fluoromethane, difluoromethane-formaldehyde and trifluoromethane-benzene. These features have been useful to describe their intermolecular interactions (weak hydrogen bonds or halogen bonds), and to size the potential energy surfaces of their internal motions. The rotational spectrum of pyridine-methane pointed out that methane prefers to locate above the ring and link to pyridine through a C-H•••π weak hydrogen bond, rather than the C-H•••n interaction. This behavior, typical of complexes of pyridine with rare gases, suggests classifying CH4, in relation to its ability to form molecular complexes with aromatic molecules, as a pseudo rare gas. The conformational equilibria of three bi-molecules of carboxylic acids, acrylic acid-trifluoroacetic acid, difluoroacetic acid-formic acid and acrylic acid-fluoroacetic acid have been studied. The increase of the hydrogen bond length upon H→D isotopic substitution (Ubbelohde effect) has been deduced from the elongation of the carboxylic carbons C•••C distance. The van der Waals complex tetrahydrofuran-krypton shows that the systematic doubling of the rotational lines has been attributed to the residual pseudo-rotation of tetrahydrofuran in the complex, based on the values of the Coriolis coupling constants, and on the type (mu_b) of the interstate transitions.

Chemistry can contribute, in many different ways to solve the challenges we are facing to modify our inefficient and fossil-fuel based energy system. The present work was motivated by the search for efficient photoactive materials to be employed in the context of the energy problem: materials to be utilized in energy efficient devices and in the production of renewable electricity and fuels. We presented a new class of copper complexes, that could find application in lighting techhnologies, by serving as luminescent materials in LEC, OLED, WOLED devices. These technologies may provide substantial energy savings in the lighting sector. Moreover, recently, copper complexes have been used as light harvesting compounds in dye sensitized photoelectrochemical solar cells, which offer a viable alternative to silicon-based photovoltaic technologies. We presented also a few supramolecular systems containing fullerene, e.g. dendrimers, dyads and triads.The most complex among these arrays, which contain porphyrin moieties, are presented in the final chapter. They undergo photoinduced energy- and electron transfer processes also with long-lived charge separated states, i.e. the fundamental processes to power artificial photosynthetic systems.

The development of safe, high energy and power electrochemical energy-conversion systems can be a response to the worldwide demand for a clean and low-fuel-consuming transport. This thesis work, starting from a basic studies on the ionic liquid (IL) electrolytes and carbon electrodes and concluding with tests on large-size IL-based supercapacitor prototypes demonstrated that the IL-based asymmetric configuration (AEDLCs) is a powerful strategy to develop safe, high-energy supercapacitors that might compete with lithium-ion batteries in power assist-hybrid electric vehicles (HEVs). The increase of specific energy in EDLCs was achieved following three routes: i) the use of hydrophobic ionic liquids (ILs) as electrolytes; ii) the design and preparation of carbon electrode materials of tailored morphology and surface chemistry to feature high capacitance response in IL and iii) the asymmetric double-layer carbon supercapacitor configuration (AEDLC) which consists of assembling the supercapacitor with different carbon loadings at the two electrodes in order to exploit the wide electrochemical stability window (ESW) of IL and to reach high maximum cell voltage (Vmax). Among the various ILs investigated the N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR1(2O1)TFSI) was selected because of its hydrophobicity and high thermal stability up to 350 °C together with good conductivity and wide ESW, exploitable in a wide temperature range, below 0°C. For such exceptional properties PYR1(2O1)TFSI was used for the whole study to develop large size IL-based carbon supercapacitor prototype. This work also highlights that the use of ILs determines different chemical-physical properties at the interface electrode/electrolyte with respect to that formed by conventional electrolytes. Indeed, the absence of solvent in ILs makes the properties of the interface not mediated by the solvent and, thus, the dielectric constant and double-layer thickness strictly depend on the chemistry of the IL ions. The study of carbon electrode materials evidences several factors that have to be taken into account for designing performing carbon electrodes in IL. The heat-treatment in inert atmosphere of the activated carbon AC which gave ACT carbon featuring ca. 100 F/g in IL demonstrated the importance of surface chemistry in the capacitive response of the carbons in hydrophobic ILs. The tailored mesoporosity of the xerogel carbons is a key parameter to achieve high capacitance response. The CO2-treated xerogel carbon X3a featured a high specific capacitance of 120 F/g in PYR14TFSI, however, exhibiting high pore volume, an excess of IL is required to fill the pores with respect to that necessary for the charge-discharge process. Further advances were achieved with electrodes based on the disordered template carbon DTC7 with pore size distribution centred at 2.7 nm which featured a notably high specific capacitance of 140 F/g in PYR14TFSI and a moderate pore volume, V>1.5 nm of 0.70 cm3/g. This thesis work demonstrated that by means of the asymmetric configuration (AEDLC) it was possible to reach high cell voltage up to 3.9 V. Indeed, IL-based AEDLCs with the X3a or ACT carbon electrodes exhibited specific energy and power of ca. 30 Wh/kg and 10 kW/kg, respectively. The DTC7 carbon electrodes, featuring a capacitance response higher of 20%-40% than those of X3a and ACT, respectively, enabled the development of a PYR14TFSI-based AEDLC with specific energy and power of 47 Wh/kg and 13 kW/kg at 60°C with Vmax of 3.9 V. Given the availability of the ACT carbon (obtained from a commercial material), the PYR1(2O1)TFSI-based AEDLCs assembled with ACT carbon electrodes were selected within the EU ILHYPOS project for the development of large-size prototypes. This study demonstrated that PYR1(2O1)TFSI-based AEDLC can operate between -30°C and +60°C and its cycling stability was proved at 60°C up to 27,000 cycles with high Vmax up to 3.8 V. Such AEDLC was further investigated following USABC and DOE FreedomCAR reference protocols for HEV to evaluate its dynamic pulse-power and energy features. It was demonstrated that with Vmax of 3.7 V at T> 30 °C the challenging energy and power targets stated by DOE for power-assist HEVs, and at T> 0 °C the standards for the 12V-TSS and 42V-FSS and TPA 2s-pulse applications are satisfied, if the ratio wmodule/wSC = 2 is accomplished, which, however, is a very demanding condition. Finally, suggestions for further advances in IL-based AEDLC performance were found. Particularly, given that the main contribution to the ESR is the electrode charging resistance, which in turn is affected by the ionic resistance in the pores that is also modulated by pore length, the pore geometry is a key parameter in carbon design not only because it defines the carbon surface but also because it can differentially “amplify” the effect of IL conductivity on the electrode charging-discharging process and, thus, supercapacitor time constant.

This work reports on the study of the products obtained by the plasma treatment of methane mixtures or benzene mixtures in a coaxial cylindrical dielectric barrier discharge reactor at atmospheric pressure. The plasma products have been analyzed by spectroscopic and mass spectrometric techniques (GC-MS, FT-IR, NMR, MALDI-TOF MS). Moreover, in this work we report the plasma phase characterization in a parallel plate DBD reactor by using OES and LIF tecniques.

This thesis presents experimental studies, based on guided ion beam mass spectrometric techniques and coupled to theoretical interpretations by quantum chemistry, on ionic mechanisms for the molecular growth of aromatic hydrocarbons with a particular relevance for understanding the formation of large molecules in ionized gases such as planetary iono-spheres, plasmas and combustion systems. The starting point of this dissertation is a study of the reactivity of naphthyl cation C10H7+ with benzene. Ion-molecule reactions leading to hydrocarbon growth via the formation of new C-C bond are studied with special reference to the association product C16H13+. Another experiment in this dissertation concerns the reactivity of the C12H9+ ion with benzene. The growth of hydrocarbon ions up to C18H15+ species via C–C bond forming reactions is observed. The adduct formation route is found to be exothermic and barrierless, while other products are found to have energy barriers. The last topic addressed in this thesis is the experimental investigation of the possible formation mechanisms of the ion C12H10O+, observed in benzene/air plasma corona discharges at atmospheric pressure.

Collisions with He+ are an important pathway for the destruction of complex organic molecules in the interstellar medium (ISM). We have carried out dissociative charge transfer reactions of He+ with two oxygen containing organic molecules, ubiquitous in ISM: dimethyl ether (DME, CH3OCH3 ) and methyl formate (MF, HCOOCH3). Since they have a prebiotic relevance, several models were developed to explain how these molecules are formed and destroyed in the ISM. The reactions have been investigated by using the home-built Guided-Ion Beam Mass Spectrometer (GIB-MS) apparatus. Absolute cross sections and branching ratios of the products have been measured as a function of the collision energy in the hyperthermal energy range (i.e. from about 0.1 eV to 7 eV). The presence of the molecular ion was not observed among the products for these reactions, which means that the nascent DME and MF radical cations are formed in a dissociative state. Insights on both the charge transfer processes have been obtained by investigating the nature of the non-adiabatic transitions between the reactant and product potential energy surfaces (PES). The PES has been represented by using a semi-empirical method to model the inter-molecular interactions. To explain the experimental evidence, two excited states of DME and MF radical cations have been invoked: He+ captures an electron from inner valence orbitals of both the organic molecules, having binding energies ~10 eV higher than the HOMO. An improved Landau-Zener-StÃ1⁄4ckelberg model has been developed to obtain the total integral cross-section to be compared with the experimental results. Inter-molecular interaction and electron densities of the orbitals involved in the reaction turned out to be key points to describe the dynamics of the two studied dissociative charge transfers. A very good agreement is obtained between the experimental and calculated total cross-sections at low collision energy, which is the most relevant range for the interstellar environment. These results represent a significant starting point to estimate rate constants for the total dissociation of DME and MF by collisions with He+ ions in the ISM at low temperatures.

In this work, two types of nano-structured TiO2 layers were obtained by two different methods. First, during an exploratory study, a set of nano-columnar TiO2 films and niobium doped TiO2 films was obtained on stainless steel, by a RF reactive sputtering technique. The argon gas is ionized by a high negative voltage applied to the TiO2 target (cathode), and a plasma is created between the cathode and the substrate (anode). Positively charged ions (Ar+) are accelerated toward the TiO2 target (a co-target Nb is placed beside the TiO2 cathode for Nb doping) and their impact sputters atoms off the target. These atoms travel across the chamber and a fraction of them land on stainless steel, resulting in a film TiO2 and Nb-doped film TiO2. With adjusting the RF power applied on the co – target, different concentrations of Nb in the TiO2 film could be controlled. The results of EIS (Electrochemical Impedance Spectroscopy) mainly showed the presence of a barrier layer (junction metal/semiconductor or metal/oxide/semiconductor) between the TiO2 layer and the stainless steel in the absence and presence of niobium. The carrier density is estimated at almost 1018 cm-3. In the second part of this thesis, two types of TiO2 nano-tubular arrays with nanotubes (NT) aligned perpendicular to the titanium substrate were obtained by anodization of a titanium foil, in two different solutions containing fluoride ions. The NT obtained in a tetrabutylammonium / formamide solution (named: TiO2-NT(TB)) are rough, while the second solution, ethylene glycol , allows to synthesize smoother and denser tubes (named: TiO2-NT(EG)). All the nanotubular arrays were characterized by EIS and showed in the high frequency range a contribution related to the presence of surface states, and a contribution at low frequencies related to the capacity of the space charge layer. In the dark, in the Na2SO4 solution with neutral pH, the EIS study of TiO2-NT (TB) anatase showed that these two contributions vary with the applied potential. The capacity of surface states varied exponentially in a wide range of potential, but in addition the presence of a localized energy state in the gap could be evidenced. This localized state is the signature of the adsorption of molecular water. After UV exposure during 3h, and back to the dark, the quasi irreversible disappearance of the localized energy states is related to photo-induced adsorbed water dissociation at some sites on the surface of NT. Furthermore, the increase by a factor 112 of the capacity of the space charge layer was observed after UV exposure. This increase can be explained by the photo activation of the surface of NT, which was inactive before UV exposure. This activation is related to the dissociation of adsorbed molecular water and the insertion of hydrogen into the walls of NT. A geometric model considering the variation of the band bending taking place inside the wall of NT is proposed to replace the classical Mott-Schottky relation, which is only valid for a plate condensator. This model allows understanding the variation of the space charge layer as a function of the applied potential. With this new model, a carrier density of about 1018 cm-3 et 1020 cm-3 respectively before and after UV illumination were determined, confirming that the photo-induced activation of the wall of NT is linked to the phenomenon of doping due to hydrogen insertion. In the case of TiO2 –NT(EG), the contribution of adsorption of molecular water was not observed. The spectrum of EIS before and after UV exposure did not show a significant change and the capacities of space charge layer after illumination only increased by a factor 8. The simulation with the model shows that the carrier density is about 1020cm-3 before and after illumination. In other words, these tubes of TiO2 –NT(EG), are already activated before illumination and the photo-induced effects are less important compared to the TiO2 –NT(TB) array. For a better identification of the chemical nature of the surface state in the case of rough tubes of TiO2 –NT(TB), EIS measurements were performed in the same manner, but in acidic (pH=3.5) and basic (pH=12.5) media, in order to compare the behaviour to that observed in the neutral Na2SO4 solution. In the alkaline electrolyte, the band bending varies only slightly with the applied potential, reflecting a shift of band edge and the filling/emptying of the surface states during polarization. Moreover, the exponential distribution of capacities of surface states is more spread out (850 meV) in alkaline solution than in the neutral solution (257meV), showing clearly the particular role of the OH groups at the surface of the tubes. In the acidic electrolyte, a phenomenon of diffusion –insertion of protons should be taken into account for interpreting the spectra of EIS. H atoms play the role of electron donors able to increase the carrier density in the wall of the tubes. The comparison between the behaviours in the 3 media clearly associates the surface states to hydroxyl groups. In the last part of this thesis, experiments were performed on TiO2 –NT(TB) in a NaOH electrolyte, using Intensity Modulated Photocurrent Spectroscopy (IMPS), and the results are discussed in comparison with a thin compact film deposed on a titanium foil par PVD.

This work shows that it is possible to fabricate phosphate-based planar wave-guides activated by rare earth ions both by sol-gel and RF-sputtering techniques. The objective of this thesis has been to evaluate various methodologies for fab-rication Phosphorous-based planar waveguides. In this context sol-gel and RF-sputtering techniques for planar waveguides fabrication has been investigated. RF-process has been optimized. In case of sol-gel technique a further thermo-dynamical study is required. Each of technique has drawbacks, in sol-gel method the principal question is related to the kinetics of the reaction, since it is too fast, to better control of the reaction rates, and better adjustment of the technological films fabrication, which effects on spectroscopic properties of the waveguiding systems: losses, refractive index. In case of RF-sputtering is no-ticeable that the refractive index is low, and the losses are less than 0.2 dB/cm, however the multicomponent target material increase the complexity of the structure.

Materials are the heart of engineering, which can be defined as the creative and rational use of materials for practical purposes. Materials have had an essential role in the development of civil engineering: from the beginning of human evolution, man has used many different materials to build houses, bridges, roads and countless other structures to make his life easier. Ancient populations used the raw materials at their disposal, such as stone, clay and timber. Over the centuries, the search for new materials became increasingly important to respond to changing human needs, and men learned how to use clay to form artificial stones, cements and concretes, for instance. While hands-on familiarity rooted in tradition and crafting expertise initially drove these human activities, in modern times the need for a scientific understanding of materials prompted the birth of the material science discipline. Material science studies the composition, behavior and properties of materials to solve problems associated with their use. Engineering and material science work together to create functional, durable and beautiful structures. Among the materials used in civil engineering constructions, wood and cement have had the most important role over the centuries and they are still the main components of our infrastructures. Timber was used as a building material even by primitive man, and a few ancient temples, palaces and bridges built of wood can still be seen today. In the 20th century, although materials such as concrete had become competitive, wood retained its significant role in building. The main problem with the use of wood as a construction material concerns its possibly limited lifetime. Wood is characterized by a limited resistance to moisture and fire, the two elements responsible for the destruction of most wooden buildings in the past. Cement, and consequently concrete, is the most often used material today. The term “cement” is now used to mean a modern binder, the so-called Portland cement, patented in England in 1824. Similar binding materials were already being used from very early on ancient Mesopotamia, Egypt, Greece and Rome. Modern cement formulations have changed a great deal and can be adapted to their intended use and the surrounding environment.

In much of the literature about organic photovoltaics, the topic is framed within the current landscape of energy production and the research on these materials is cited as a possible solution to the energy crisis looming ahead. Despite being the most frequent, this is by no means the only perspective that can be offered. Indeed, the same research may also be set within the larger perspective offered by the field of functional materials. These materials are usually exploited for their particular responses to electrical, magnetic and chemical stimuli and are at the basis of many technologies fundamental to our society. The prominent position of functional materials in modern science is due to the emergence of novel technological needs that such materials have been able to satisfy thanks to their peculiar properties. These properties have been rationalised and mastered by expanding the theoretical description of the underlying physical mechanisms. This theoretical body, combined with the growth and diffusion of computational capabilities has fostered a change in the scientific paradigm underpinning the research effort. More and more, the predictive power of numerical approaches is exploited to lead the way in the exploration of the immense chemical space. The ultimate promise is to achieve the purpose-driven design of compounds thanks to which the molecular structure can be engineered before the actual synthesis to meet the demands dictated by a specific application. To fulfil this role, computational approaches need to be able to simulate the solid state properties at the most relevant time and length scales. If this can be accomplished then a reliable prediction of the performance can be achieved. The current work deals with the development and application of one such protocol, for the particular case of organic photovoltaic semiconductors. Given the specific application, the properties targeted are light absorption and charge transport. Particular effort is put in the simulation of local morphologies at scales above the molecular one to describe supramolecular organisation with sufficient resolution. In this thesis, the protocol is applied to two molecular systems employed in solar devices. Both systems have been selected on the basis of data suggesting that a detailed microscopic description of their behaviour could be highly informative about the aspects responsible for their photovoltaic performance. In particular, chapter 3 details the investigation of a small-molecule donor that has been shown in the literature to have a remarkable behaviour in absorption. While chapter 4 reports the study of a donor-acceptor dyad used as active layer in single-component solar devices with relatively high conversion efficiency. In both cases, the computational protocol has proven capable of providing a detailed microscopic description of the systems. The picture drawn has allowed to clarify the plausible mechanisms behind the observations and to rationalise these behaviours in a broader and more general theoretical framework.