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Polydimethylsiloxane (PDMS) has been irradiated by a ns pulsed IR laser in vacuum and the radiation effects induced by the coherent radiation, above a threshold fluence, produce a non-equilibrium plasma and material ablation. The laser absorption can be enhanced using gold nanoparticles (AuNPs) embedded in the polymer. The laser-generated plasma has been characterized, whereas the ion emission from both the virgin PDMS and the PDMS + AuNPs sheets has been analysed both in mass and energy. Morphological investigations, optical spectroscopy and compositional analyses have been performed. The adopted laser treatment can be employed to modify the properties of PDMS with and without AuNPs inducing a local enrichment of microcrystalline silicon in both cases.

The INFN-CIMA project deals with the employment of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) for applications in Nuclear Physics. In particular, the project aim is that to use ...

Reduced graphene oxide (rGO) is a two-dimensional material, which is attracting increasing attention due to its special properties. It can be obtained by laser or ion beam irradiations of pristine ...

A Nd:YAG laser operating at 1064 nm was used to irradiate, at different intensities, graphene oxide foils placed in vacuum and in air. The laser irradiated GO foils were analysed successively by using different techniques such as 2.0 MeV alpha particle Rutherford backscattering spectrometry, X-ray photoemission spectroscopy and SEM-EDX. In particular, in vacuum irradiated graphene oxide samples the oxygen reduction has been observed with increment of the carbon content. In air irradiated GO samples an increase in oxygen has instead been highlighted. Furthermore thermal and chemical effects are induced by the photon irradiation. Results will be presented and discussed.

Different ion beams, with energy from 2 MeV up to 16 MeV at different atomic number, have been employed to irradiate graphene oxide (GO) foils in vacuum. Due to effects of electron and nuclear ion stopping powers, the ion energy deposition reduces the irradiated GO foils and structurally modifies them. The ion bombarded GO foils X-ray diffraction (XRD) investigations have permitted to shed light on the different structural phases induced by the ion energy deposition. The changes in the GO foils pristine structure shift the diffraction main peak towards larger angles and produce new diffraction peaks indicating the presence of new phases, such as reduced GO (rGO), carbon nanotubes (CNT), amorphous carbon (a-C), onion like carbon (OLC) and probably new carbon allotropes. The obtained results indicate that the inner structure of the GO foils becomes more and more compact and dense with the absorbed dose, suggesting that the removal of the functional oxygen groups leads to a near graphite structure with a significant increase of the material mass density. The different structural phase modifications induced by the different ion beams as a function of the stopping power, fluence and dose will be presented and discussed in detail.

Different ion beams, from protons up to gold ions, with energy from 2 MeV up to 16 MeV, have been employed to irradiate graphene oxide (GO) foils in vacuum. The ion energy deposition reduces GO releasing functional oxygen groups. The effect of radiating ions – GO foils interaction has been investigated by Raman spectroscopy, X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). All the performed analyses show that both reduction and damaging depend on the fluence, the energy and the type of radiating ions. In the regime of electron stopping power the reduction is linearly dependent on the absorbed dose, while in the regime of nuclear stopping power an intense damage is produced in GO, altering the Raman spectrum and producing defects and amorphization of the material. The achieved goal was to quantify the GO's response to ionizing radiation with the aim of using the GO foil as a dosimeter for high energy ion beams.

In this paper, the synthesis of macro-porous polydimethylsiloxane (PDMS) sponges decorated with reduced graphene oxide and graphene is described using a top-down approach based on the sugar templating process. Among the multiple assets enjoyed by PDMS, its elasticity and porosity make possible the uniform dispersion of embedded graphene-based material into its structure. Where possible, the optical, surface and morphology properties of both porous PDMS composites and their not porous (bulk) counterparts have been studied. Scanning transmission ion microscopy (STIM), based on the reciprocity between the beam energy loss and the sample areal density, has been used to obtain the images of the sponge internal part. A detailed spatial resolution of the PDMS microstructure has been deduced by the areal density map. The homogeneous dispersion of the fillers was observed by scanning electron microscopy (SEM) and indirectly by light transmittance measures performed in several regions of the PDMS bulk. The reduced graphene oxide and graphene introduced into PDMS significantly improve its electrical conductivity. The porosity of the presented hybrid material holds a key role for good performances in microelectronics and biomedicine.

Measurements of nitrogen diffusion coefficient in graphene oxide (GO) and reduced graphene oxide (rGO) have been performed at different temperatures ranging between 21 °C and 101 °C. GO and rGO foils have been prepared as thin foils with 15 μm in thickness, total surface of about 5 cm2 and active diffusion surface of about 20 mm2. The rGO foils have been obtained by thermal annealing at 170 °C for 30 min in air. The measured room temperature diffusion coefficients, of 3.43 × 10−4 cm2/s for GO and 5.1 × 10−4 cm2/s for rGO, and, at 101 °C, of 5.22 × 10−4 cm2/s for GO and 10.7 × 10−4 cm2/s for rGO, have been obtained with a simple experimental set-up measuring the gas pressure gradient applied to the two faces of the thin foils versus the time. The rGO foils show a significant increasing of the diffusion coefficients with respect to the pristine GO due to the removing of water and some functional oxygen groups which determines the aperture of nanochannels through which the N2 gas diffuses. The thermal activation energy of nitrogen diffusion is evaluated for the two investigated materials. The experimental apparatus to measure the diffusion coefficients, the obtained results, their correlation with the graphene sheets structure and the comparison with the literature data are presented and discussed.

A simple, cost-effective approach to realize a sensitive temperature sensor based on IR laser reduced graphene oxide (IRLrGO) is reported. The sensor has been obtained by irradiating a graphene oxide (GO) film, placed between two thin glass substrates, with a continuous wave diode laser operating at 970 nm along its entire length. A conductive strip, 13 mm long, 300 μm wide and 7 μm thick, has been generated by moving the GO film on an X-Y translator stage with a given velocity with respect to the fixed laser fiber tip position. The laser treatment has given rise to the GO reduction confirmed by the resistance R measurements as well as from SEM, EDX, ATR-FTIR and Raman analyses. The temperature dependence of the conductive strip resistance has been measured in air from 30ˆC to 80ˆC and in high vacuum from 80 K to 300 K. The sample acts as a sensitive and low mass Resistance Temperature Detector (RTD). Such a sensor is biocompatible and requires a very low bias (

Graphene oxide (GO) micrometric foils have been prepared using a graphene oxide solution. A pulsed IR laser at 970 nm wavelength, with a 100 ms pulse duration and an energy between 50 mJ and 0.7 J, has been employed to irradiate the micrometric GO foils in air. Pulsed IR laser irradiation of GO foils promotes the GO reduction in air and, when the GO foils are tightened between two transparent and thin flat glasses, it permits to realize electrically conductive strips, labelled as rGO. Measurements of laser ablation yield in air as a function of the pulse energy, analysis of elemental composition of the samples before and after the irradiation and morphological characterization have been performed. An estimation of both the temperature induced by the laser treatment and the penetration depth is presented. The so-obtained rGO foils can find many interesting applications in microelectronics, engineering and bio-medicine as sensors, detectors, ion strippers and dosimeters.

A new type of ion dosimeter based on graphene oxide (GO) foils is presented and discussed. GO is biocompatible, stable, tissue equivalent and has special chemical and physical properties. The ion i...

Two well-established electrical insulators, graphene oxide and poly(methylmethacrylate) (PMMA) have been selectively exposed to controlled energy and fluence of ions. Ion micro beam has been propos...

An overview of physical investigations of cultural heritage samples using ion and laser beams performed in the frame of the international collaboration between the University of Messina (Italy) and the Nuclear Physics Institute-ASCR (Czech Republic) is presented. Solid samples are analysed in high vacuum using particle induced X-ray emission, Rutherford backscattering spectrometry, elastic recoil detection analysis, prompt γ activation analysis, nuclear reaction analysis, laser ablation, mass spectrometry, scanning electron microscopy, and many more. The elemental composition of the sample, the trace elements, the depth profiles, the morphology and the comparison between samples and references are reported. Both electron and ion microbeams are employed to have details of the spatial distribution maps of elements of interest.

Graphene oxide (GO) is an electrical insulator as most of the carbon atoms in this material are sp3-hybridized. Its physical, optical and chemical properties depend on the type and degree of reduction process. Presently, copper ion irradiation of GO foil has been performed at Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf to investigate the behavior of a set of GO foils under this irradiation at low energy and different fluences up to 5 × 1016 ions/cm2. The compositional and optical properties of graphene oxide have been studied as a function of the fluences of implanted copper ions in the wavelength range 400–1000 nm. The results of ellipsometry microscopy, helium Rutherford backscattering spectroscopy, elastic recoil detection analysis, Raman spectroscopy and SEM-EDX measurements will be presented and discussed.

Measurements of electrical conductivity were carried out at temperatures ranging between 77 K and 450 K on high vacuum thermal reduced graphene oxide (rGO) films. The investigated samples were characterized in composition and structure before being analyzed in terms of electrical conduction. Their electrical conductivity was also measured in air at room temperature. Measurements have demonstrated that at first graphene oxide (GO) was not stable both in air and vacuum. It stabilized after having been subjected to 7 thermal cycles under high vacuum conditions, about 10−7 torr, up to a Tmax of 450 K. At room temperature the initial GO material had a very low conductivity, of the order of 10−10 Ω−1 x cm−1, which increased to about 2.5 Ω−1x cm−1 when it was thermal stabilized in rGO. The stabilization process, induced by the high vacuum heating procedure, seems due to a good reduction of GO, which gives rise to such expansion of the conjugated π-electron system that a band-like transport with small thermal activation energies (Ea = 10–50 meV) occurs. The performed electrical conductivity measurements are presented and discussed.

Advanced targets based on thin films of graphene oxide covered by metallic layers have been irradiated at high laser intensity ($\ensuremath{\sim}{10}^{19}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) with 40 fs laser pulses to investigate the forward ion acceleration in the target normal sheath acceleration regime. A time-of-flight technique was employed with silicon-carbide detectors and ion collectors as fast on-line plasma diagnostics. At the optimized conditions of the laser focus position with respect to the target surface was measured the maximum proton energy using Au metallic films. A maximum proton energy of 2.85 MeV was measured using the Au metallization of 200 nm. The presence of graphene oxide facilitates the electron crossing of the foil minimizing the electron scattering and increasing the electric field driving the ion acceleration. The effect of plasma electron density control using the graphene oxide is presented and discussed.

Reduced graphene oxide (rGO) films can be employed as ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivity, low density, high mechanical resistance and high stability. Thin graphene oxide (GO) films with a sub-micron thickness have been synthesized and transformed into reduced GO (rGO) by ion beam irradiations. Physical characterizations of the pristine and ion irradiated GO films have been performed. Measurements of stripping efficiency have been carried out by using helium, lithium, carbon and oxygen ion beams. The rGO stripper films demonstrate a significantly high charge production, comparable to that of the graphite films but with the advantage of a longer lifetime.

In recent years graphene and its derivatives, have attracted scientific interest due to their unique properties. This study is to explore the quality of synthesized graphene oxide and reduced graphene oxide foils under the irradiation of protons and helium ions of the same energy and current. Fully characterizations by Raman spectroscopy, Rutherford backscattering spectrometry and Elastic recoil detection analysis and the relative results are presented. The effects of parameters, such as type of ions, their current and irradiation time, are studied. The quality of large-scale fabrication of graphene oxide and reduced graphene oxide (rGO) is important for industrial and research applications of these materials. An overview on the changes in the optical property and electron conductivity of graphene oxide and reduced graphene oxide under irradiation by protons, helium and carbon ions are also summarized.

Graphene oxide (GO) is prepared as a self-supporting thin film by a liquid solution of GO. The so-obtained GO films have been characterized in terms of thickness and density. The GO film composition and trace elements have been measured with Rutherford backscattering spectrometry (RBS) and Elastic recoil detection analysis (ERDA), using MeV helium ion beams. The presence of crystalline and amorphous phases has been also investigated with X-ray diffraction (XRD) and the morphology by scanning electron microscopy (SEM). Information about the GO film structure, oxidation degree and thickness has been deduced by means of Fourier transform infrared spectroscopy (FT-IR), Raman and optical spectroscopy (ultraviolet-visible-near infrared spectroscopy, UV-Vis-nIR). In particular, the GO film thickness varies from sub-micrometric values up to micrometric ones. Furthermore, the GO film heating in air up to 60 °C produces oxidation effects as deduced from the interpretation of our data.

Modifications induced by nanosecond Nd:YAG laser irradiation in the graphene oxide properties were investigated. To correlate the effects of laser irradiation with the modifications of the structural, chemical and electrical properties of graphene oxide, 2.5 MeV alpha particle and 2.0 MeV proton beams in Rutherford backscattering spectrometry and elastic recoil detection analysis, and also X-ray photoemission spectroscopy, have been employed. A high ratio of carbon to oxygen atoms was measured in the irradiated graphene oxide, with respect to the virgin one. The localized reduction of graphene oxide film is promising for patterning techniques useful for the graphene-based devices production.

Reduced graphene oxide (rGO) films can be employed as thin ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivities, low density, high mechanical resistance and high stability. The preparation method of the graphene-based films and their physical characterization are presented and discussed. Thin graphene oxide (GO) films with a thickness of from 0.5 up to 2.0 μm have been synthesized and studied to be used as an ion extractor (stripper) in the 3.0 MV Tandetron of the CANAM Laboratory at the Nuclear Physics Institute in Rez, Czech Republic. GO is transformed to rGO also by low ion beam doses. Measurements of stripper efficiency, as the ion transmission factor of films, have been carried out by accelerating different ions, from helium to carbon, having energies from 1.0 up to 16 MeV, and by using different charge states and a current density ranging between about 10 nA/cm2 and 2 μA/cm2. The ion fluence at which the so-obtained graphene oxide films can be undergone exceeds a dose of 1 × 1016 particles/cm2. Furthermore, these stripper films have demonstrated a significantly high charge production, comparable to that of the graphite films. However, the higher mechanical resistance represents an undiscussed advantage with respect to the graphite films.