Gian Carlo Gazzadi

Cu@CaF2 plasmonic nanoparticle (NP) films are physically synthesized, and their morphology, and electronic and optical properties are thoroughly investigated. Cu NPs are generated using a gas aggregation source assisted by magnetron sputtering, while CaF2 coatings are deposited by thermal evaporation. Scanning Electron Microscopy, Atomic Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) provide a clear picture of the film morphology. The Cu NP shapes remain substantially unaffected by the deposition of CaF2, acting as nucleation centers for fluoride growth, which effectively forms a protective shell. With increasing CaF2 thickness, the shells extend to form islands, which eventually coalesce into a complex film morphology. Computer vision methods based on Mask Regional convolutional neural network, one of the leading deep learning architectures for object detection, are employed to fully automate particle analysis, exploiting its capabilities to perform detailed statistical evaluation of NP size and shape from a large number of images. AFM and TEM reveal that the NPs have a lateral size of 〈d〉 = 13.8 ± 0.9 nm and an oblate spheroid shape with aspect ratio = d/h ≈ 1.2. In situ XPS data show that the chemical state of the NPs is unaffected by the presence of CaF2. Finally, optical data obtained with a UV–vis–near IR spectrometer and simulated using the Maxwell–Garnett approximated extinction cross section demonstrate that the Cu localized surface plasmon resonance remains robust under prolonged atmospheric exposure, a fundamental property that is crucial for applications in photovoltaics and optoelectronics.

The Aharonov–Bohm (AB) effect is one of the most striking features of quantum physics, and it is of critical importance to elucidate the role of the electromagnetic potential and its physical meaning. In spite of the fact that it was first proposed in 1949, up to now it has only been demonstrated for electrons and neutrons. We propose the realization of an experiment to study the AB effect for the antiproton, which will have the double feature of being a non-elementary charged particle and at the same time an antiparticle. The experiment will be conducted in collaboration with the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) group at the CERN AD (Antiproton Decelerator), making use of a slow antiproton beam.

Rotational invariance is a fundamental aspect of symmetry in scattering processes from atomic potentials. Here, we present an approach for measuring orbital angular momentum (OAM), a key descriptor of rotational symmetry, during measurements of atomic transitions. We use an electron optical OAM sorter in combination with electron energy-loss spectroscopy and model-based fitting to separately measure the π* and σ* antibonding transitions in hexagonal boron nitride on the atomic scale. This approach also offers prospects for efficient and atomically-resolved magnetic chiral dichroism measurements.

Hydrogenated diamond‐like carbon (H‐DLC) coatings are extensively employed in high‐performance tribological applications, yet their frictional behavior in humid environments remains a critical limitation. A scalable and industrially viable strategy based on graphitic nanodiamonds (Gr‐NDs) is here proposed, enabling humidity‐resistant ultralow friction (coefficient of friction <0.1) without requiring controlled atmospheres or complex surface treatments. This approach is distinct from many recent methods involving the deposition of nanoparticles and 2D materials, which often fail under humid conditions. Gr‐NDs leverage their intrinsic core–shell nanostructure to promote the in operando formation of a peculiar graphitic transfer layer (TL), directly enhancing interfacial lubrication. High‐resolution transmission electron microscopy and Raman spectroscopy confirm that these nanostructures are effectively retained within the TL, ensuring superior wear resistance and friction reduction. Furthermore, spectroscopic analysis reveals that moderate tribochemical oxidation stabilizes the TL, extending its durability under realistic operating conditions. This work establishes Gr‐NDs as a disruptive functional additive for H‐DLC coatings, offering a robust, scalable, and environmentally friendly solution for next‐generation tribological systems in demanding mechanical applications.

In light optics holographic beam shaping has been largely used to obtain complicated wavefronts [1]\ud and vortex beams. In the last years holograms have been used in the electron vortex beam generation\ud [2]. We have recently improved the technology of hologram fabrication by means of “phase hologram”\ud [3] replacing the amplitude hologram so far used. Phase holograms appropriately change the phase of\ud the incident wavefront by a modulation of thickness in a silicon nitride thin membrane. Beyond vortex\ud generation, holograms can have a large range of applications. As an example in this work we report on\ud the production of a Bessel beam in the Fresnel diffraction regime [4].\ud Bessel beams have many interesting properties most of which derived from being the Fourier transform\ud of a ring. In this sense they can be considered as the extreme case of hollow cone illumination. However\ud while the production of hollow cone probes requires a strong reduction of the electron beam current by\ud the use of an obstructing aperture, the holographic approach permits to produce high quality Bessel\ud beams with only marginal intensity losses. In particular by the use of phase holograms we could\ud demonstrate up to 40% efficiency. In these conditions the generated beam is competitive with normal\ud aperture limited approaches in terms of intensity.\ud Fig 1a shows the FIB-nanofabricated hologram that has been positioned in the second condenser\ud aperture of a FEI Tecnai F20 operated at 200 kV. Fig 1b is an image of the logarithm of the intensity of\ud the Bessel beam showing the characteristic fringes aside from the central peak. The obtained probe size\ud is in this case 0.5 nm. But we will show that the beam can be potentially scaled to 0.1 nm for larger\ud convergences. In Fig 1c the Fraunhofer diffraction of the hologram is also shown demonstrating that the\ud probe is the Fourier transform of a tiny ring. The calculated convergence is here 1.9 mrad.\ud This beam can be exploited in many applications. One of the main advantages of this is that the probe\ud shape is, to large extent, independent from spherical aberration, chromatic aberration and from defocus;\ud the other is that for the given convergence Bessel beam provide the minimal probe size regardless of\ud spherical aberration.\ud Fig 2a shows the transfer function of a microscope with a conventional probe (with and without\ud aberration) with convergence 15 mrad and with a Bessel probe. Clearly the Bessel probe can produce\ud advantages in the high frequency region. Fig 2b is a simulation of STEM-HAADF images for a Au\ud particle with the two kinds of probes as in fig 2a. Using the Bessel beams in fig 1a we obtained the\ud STEM image in fig 2c that demonstrates that, in spite of the presence of other diffraction peaks, a good\ud quality scan of a sample (a Si-SiO STI structure) can be obtained with a resolution better than 2nm\ud (measured as the blurring of the contrast features). In fact the transmitted and other diffraction beam are\ud completely delocalized and do not contribute significantly to the contrast

A novel structure for Organic Thin-Film Transistor (OTFT) is here presented. The devices are fabricated using a one-mask, photolithographic self-alignment technique which can be performed with standard photoresists and without further chemical treatments. This technique, combined with a novel technology for the realization of low voltage OTFTs, allows a dramatic reduction of the parasitic capacitances thus leading to a remarkable cut-off frequency. In this paper, the main electrical parameters of low voltage, self-aligned devices are reported, and a complete frequency characterization of the devices is given. These characteristics make the reported approach suitable for the development of basic circuitries for frequency applications.