Manufacture of a MoO3 coated copper made device

In this report we describe the procedure to manufacture a model of a cylindrical RF cavity made in copper and coated with a 100 nm thick layer of molybdenum trioxide. The device is 100 mm long, has an internal diameter of 60 mm and an external diameter of 80 mm. The cylindrical device was carefully divided into four sections to make possible the coating on the internal curved surfaces polished to a roughness < 10 nm. The molybdenum trioxide has been deposed utilizing a thermal evaporation technique with a dedicated high vacuum chamber equipped with a high-temperature Alumina crucible working in the temperature range of 400° - 600° C

Manufacture of a MoO3 coated copper made device

We describe the procedure to manufacture a model of a cylindrical RF cavity made in copper and coated with a 100 nm thick layer of molybdenum trioxide. The device is 100 mm long, has an internal diameter of 60 mm and an external diameter of 80 mm. The cylindrical device was carefully divided into four sections to make possible the coating on the internal curved surfaces polished to a roughness < 10 nm. The molybdenum trioxide has been deposed utilizing a thermal evaporation technique with a dedicated high vacuum chamber equipped with a high-temperature Alumina crucible working in the temperature range of 400° - 600° C

Exploiting the Properties of Ti-Doped CVD-Grown Diamonds for the Assembling of Electrodes

A hybrid chemical vapor deposition (CVD)‐powder flowing technique specifically developed in lab has been employed to produce high‐quality polycrystalline diamond layers containing Ti inclusions. Morphology, structural features, and surface composition of nanocomposite diamond‐based samples produced by different growth times have been analyzed by scanning electron microscopy, Raman and Auger spectroscopy, respectively. The CVD methodology adopted for the Ti incorporation in the diamond lattice does not perturb the crystalline quality of the diamond matrix, therefore maintaining the outstanding properties of the C‐sp3 phase. The functional properties of the nanocomposite layers have been tested by nanoindentation and I–V measurements. The electrochemical performance of the diamond/Ti electrodes is evaluated by performing cyclic voltammetry in different media, namely, acidic, neutral, and basic aqueous solutions, and by estimating the rate constant of heterogeneous electron transfer to diamond surface for the ferro/ferricyanide redox couple. The rather good electrochemical performances, the mechanical strength, and the chemical inertness of the Ti‐doped diamond electrodes produced by the CVD approach, comply with the whole set of technological requirements, such as robustness, long durability, and biocompatibility, required for use in hostile environments or in biological systems

A new approach to deposit homogeneous samples of asbestos fibres for toxicological tests in vitro

In this paper we describe the results obtained with a novel method to prepare depositions of asbestos fibres for toxicological tests in vitro. The technique is based on a micro-dispenser, working as an inkjet printer, able to deposit micro-sized droplets from a suspension of fibres in a liquid medium; we used here a highly evaporating liquid (ethanol) to reduce the experimental time, however other solvents could be used. Both the amount and spatial distribution of fibres on the substrate can be controlled by adjusting the parameters of the micro-dispenser such as deposition area, deposition time, uniformity and volume of the deposited liquid. Statistical analysis of images obtained by optical and scanning electron microscopy shows that this technique produces an extremely homogeneous distribution of fibers. Specifically, the number of deposited single fibres is maximized (up to 20 times), a feature that is essential when performing viability tests where agglomerated or untangled fibrous particles need to be avoided

Extraordinary optical transmittance generation on Si3N4 membranes

Metamaterials are attracting increasing attention due to their ability to support novel and engineerable electromagnetic functionalities. In this paper, we investigate one of these functionalities, i.e. the extraordinary optical transmittance (EOT) effect based on silicon nitride (Si3N4) membranes patterned with a periodic lattice of micrometric holes. Here, the coupling between the incoming electromagnetic wave and a Si3N4 optical phonon located around 900 cm-1 triggers an increase of the transmitted infrared intensity in an otherwise opaque spectral region. Different hole sizes are investigated suggesting that the mediating mechanism responsible for this phenomenon is the excitation of a phonon-polariton mode. The electric field distribution around the holes is further investigated by numerical simulations and nano-IR measurements based on a Scattering-Scanning Near Field Microscope (s-SNOM) technique, confirming the phonon-polariton origin of the EOT effect. Being membrane technologies at the core of a broad range of applications, the confinement of IR radiation at the membrane surface provides this technology platform with a novel light-matter interaction functionality

Optical properties of two-dimensional tin nanosheets epitaxially grown on graphene

Heterostacks formed by combining two-dimensional materials show novel properties which are of great interest for new applications in electronics, photonics and even twistronics, the new emerging field born after the outstanding discoveries on twisted graphene. Here, we report the direct growth of tin nanosheets at the two-dimensional limit via molecular beam epitaxy on chemical vapor deposited graphene on Al2O3(0001). The mutual interaction between the tin nanosheets and graphene is evidenced by structural and chemical investigations. On the one hand, Raman spectroscopy indicates that graphene undergoes compressive strain after the tin growth, while no charge transfer is observed. On the other hand, chemical analysis shows that tin nanosheets interaction with sapphire is mediated by graphene avoiding the tin oxidation occurring in the direct growth on this substrate. Remarkably, optical measurements show that the absorption of tin nanosheets show a graphene-like behavior with a strong absorption in the ultraviolet photon energy range, therein resulting in a different optical response compared to tin nanosheets on bare sapphire. The optical properties of tin nanosheets therefore represent an open and flexible playground for the absorption of light in a broad range of the electromagnetic spectrum and technologically relevant applications for photon harvesting and sensors.Comment: 14 pages, 7 figure

Molybdenum oxides coatings for high demanding accelerator components

Large electric gradients are required for a variety of new applications, notably including the extreme high brightness electron sources for X-ray free electron lasers (FELs), radio-frequency (RF) photo-injectors, industrial and medical accelerators, and linear accelerators for particle physics colliders. In the framework of the INFN-LNF, SLAC (USA), KEK (Japan), UCLA (Los Angeles) collaboration, the Frascati National Laboratories (LNF) are involved in the modelling, development, and testing of RF structures devoted to particles acceleration by high gradient electric fields of particles through metal devices. In order to improve the maximum sustainable gradients in normal-conducting RF-accelerating structures, both the RF breakdown and dark current should be minimized. To this purpose, studying new materials as well as manufacturing techniques are mandatory to identify better solutions to such extremely requested applications. In this contribution, we discuss the possibility of using a dedicated coating on a solid copper sample (and other metals) with a relatively thick film to improve and optimize breakdown performances and to minimize the dark current. We present here the first characterization of MoO3 films deposited on copper by pulsed-laser deposition (PLD)

Secondary Structures of MERS-CoV, SARS-CoV, and SARS-CoV-2 Spike Proteins Revealed by Infrared Vibrational Spectroscopy

All coronaviruses are characterized by spike glycoproteins whose S1 subunits contain the receptor binding domain (RBD). The RBD anchors the virus to the host cellular membrane to regulate the virus transmissibility and infectious process. Although the protein/receptor interaction mainly depends on the spike’s conformation, particularly on its S1 unit, their secondary structures are poorly known. In this paper, the S1 conformation was investigated for MERS-CoV, SARS-CoV, and SARS-CoV-2 at serological pH by measuring their Amide I infrared absorption bands. The SARS-CoV-2 S1 secondary structure revealed a strong difference compared to those of MERS-CoV and SARS-CoV, with a significant presence of extended β-sheets. Furthermore, the conformation of the SARS-CoV-2 S1 showed a significant change by moving from serological pH to mild acidic and alkaline pH conditions. Both results suggest the capability of infrared spectroscopy to follow the secondary structure adaptation of the SARS-CoV-2 S1 to different environments

Spatially Resolved Spectral Imaging by A THz-FEL

Using the unique characteristics of the free-electron-laser (FEL), we successfully performed high-sensitivity spectral imaging of different materials in the terahertz (THz) and far-infrared (FIR) domain. THz imaging at various wavelengths was achieved using in situ spectroscopy by means of this wavelength tunable and monochromatic source. In particular, owing to its large intensity and directionality, we could collect high-sensitivity transmission imaging of extremely low-transparency materials and three-dimensional objects in the 3–6 THz range. By accurately identifying the intrinsic absorption wavelength of organic and inorganic materials, we succeeded in the mapping of spatial distribution of individual components. This simple imaging technique using a focusing optics and a raster scan modality has made it possible to set up and carry out fast spectral imaging experiments on different materials in this radiation facility