Ricerc@Sapienza

A new hybrid nanocomposite material was developed to monitor the effects of UV-C radiation on space-grade structures. Ultraviolet radiation represents one of the most critical limitations for human space exploration and survival. In particular, the UV-C band with shorter wavelengths (100-280 nm) can severely damage materials and life in space. Ultraviolet sensing films were realized using graphene nanoplatelets (GNPs) as signal transducer and DNA as biological sensitive component.

Spontaneous Raman spectroscopy is a powerful characterization tool for graphene research. Its extension to the coherent regime, despite the large nonlinear third-order susceptibility of graphene, has so far proven challenging. Due to its gapless nature, several interfering electronic and phononic transitions concur to generate its optical response, preventing to retrieve spectral profiles analogous to those of spontaneous Raman. Here we report stimulated Raman spectroscopy of the G-phonon in single and multi-layer graphene, through coherent anti-Stokes Raman Scattering.

Wafer-scale integration of reduced graphene oxide with H-terminated Si(1 1 1) surfaces has been accomplished by electrochemical reduction of a thin film of graphene oxide deposited onto Si by drop casting. Two reduction methods have been assayed and carried out in an acetonitrile solution. The initial deposit was subjected either to potential cycling in a 0.1 M TBAPF 6 /CH 3 CN solution at scan rates values of 20 mV s −1 and 50 mV s −1 , or to a potentiostatic polarization at E λ,c = −3 V for 450 s.

BACKGROUND: Chemical disinfection of surfaces and instruments for infection control in dental units is a relevant practice, especially at the time of antibiotic resistance microbes. Resistant bacteria are in fact, involved in the high incidence of healthcare-acquired infections, recognized as critical emergence in hospitals and clinics around the world.

It has recently been shown that the relaxation time of a graphene sheet is the crucial parameter that governs the radiation performance in graphene THz antennas based on either plasmonic or nonplasmonic leaky waves. Moreover, the radiating properties of these devices have always been derived assuming an ideal dipole-like source, and no full-wave and experimental results on realistic feeders have been reported, yet. To this purpose, in this work we aim at bringing the designs of graphene-based Fabry-Perot cavity leaky-wave antennas (FPC-LWAs) towards an experimental stage.

The three-dimensional potential time-domain Green’s function for a vertical electric dipole radiating in vacuum in the presence of a graphene sheet is derived in a semi-analytical form, by assuming a local Drude-like model for the graphene conductivity in the intraband regime, through a modified Cagniard-de Hoop approach. The derived expression is simple and requires only a straightforward evaluation of a finite smooth one-dimensional integral.

In this paper, a systematic design of Fabry-Perot cavity antennas based on leaky waves is proposed in the THz range. The use of different topologies for the synthesis of homogenized metasurfaces shows that a specific fishnetlike unit cell is particularly suitable for the design of efficient THz radiating devices. Accurate full-wave simulations highlight the advantages and disadvantages of the proposed geometries, thoroughly considering the bounds dictated by technological constraints and the homogenization limit as well.

Metamaterials have provided applications in spectral ranges covering radio frequencies and ultraviolet. However, most applications have been extrapolated to the visible or near-infrared after being developed at the GHz level. This is due to technological reasons since fabrication of microwave antennas is not as demanding as THz resonators or plasmonic nanostructures. Accordingly, this book has been divided into three parts. In the first part, fundamentals of metamaterials and metadevices are discussed, while describing recent advances in the field.