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Conductive tracks based on reduced graphene oxide (rGO) were induced by MeV energy helium ion microbeams in graphene oxide (GO) sheets. The computerized X-Y step motors movement of the GO foil in front of the fixed ion microbeam in a high vacuum produces a reduction of the functionalized oxygen groups, generating a graphene-like track with high electrical conductivity. The conductive track generated on the insulating matrix has a depth dependent on the range of ions used, maintains the electrical properties even under bending stress, and can electrically connect devices made of the same carbon-based material or different materials. Scanning electron microscopy, characteristic X-ray emission, electron conductivity measurements, Raman spectroscopy, surface wetting and roughness, X-ray diffraction, and optical spectroscopy are employed to investigate the ion beam modifications induced in the GO structure.

X-rays and forward ion emission from laser-generated plasma in the Target Normal Sheath Acceleration regime of different targets with 10-μm thickness, irradiated at Prague Asterix Laser System (PALS) laboratory at about 1016 W/cm2 intensity, employing a 1,315 nm-wavelength laser with a 300-ps pulse duration, are investigated. The photon and ion emissions were mainly measured using Silicon Carbide (SiC) detectors in time-of-flight configuration and X-ray streak camera imaging. The results show that the maximum proton acceleration value and the X-ray emission yield growth are proportional to the atomic number of the irradiated targets. The X-ray emission is not isotropic, with energies increasing from 1 keV for light atomic targets to about 2.5 keV for heavy atomic targets. The laser focal position significantly influences the X-ray emission from light and heavy irradiated targets, indicating the possible induction of self-focusing effects when the laser beam is focalized in front of the light target surface and of electron density enhancement for focalization inside the target.

Bismuth is a biocompatible material that can be employed in the form of nanoparticles to be used as a possible alternative contrast medium for diagnostics. In particular, it has been prepared as spherical nanoparticles in liquid solution by using the technique of the pulsed laser ablation in water. The high atomic number Bi nanoparticles in the solution show surface plasmon resonance effects, high mass absorption coefficient for soft X-ray interaction and high electron and nuclear stopping powers for electrons and ion beams. This biocompatible solution can be injected into living systems, such as mice, in order to study the up-take effect in different organs with a high contrast spatial localization of the X-ray images in the tissues in which the nanoparticles are confined. The high contrast medium for high-resolution imaging in biological systems can be also used as targeting for successive exposure to ionizing radiation during radiotherapy or hyperthermia of diseased cells. The obtained results demonstrate high contrast images of Bi nanoparticles in biological environment by using the X-ray fluorescence in the electron microscopy and the X-ray absorption in mice.

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 Technical Reports are intended mainly for internal use within the COSMO group (COSMO = Consortium for Small Scale Modeling), but also to inform other groups on model changes and research activities. The purpose of the Technical Reports is 1. to document scientific research activities, 2. to document technical changes to the model system, 3. to give an overview on new components of the model system.

The purpose of this work is the characteristic modification by ion implantation of ultra high molecular weight polyethylene, and a preliminary study of its surface. This biomedical material has been chosen for its excellent chemical and physical properties. An ultraviolet-pulsed laser of 248 nm was employed to produce, by laser ablation, C and Ti ions of different charges with current densities of the order of 10 mA/cm(2). The ions were accelerated by the application of a positive high voltage, 30 kV, on the target support to accelerate ions to implant the polyethylene surfaces up to a depth of about 200 nm. Preliminary results about surface properties indicate that implanted surfaces have higher wettability and micro-hardness values with respect to unimplanted ones

Titanium and some its alloys represent the better metallic materials with high biocompatibility useful to realise many biomedical prostheses and implants. Special fix and movable titanium based prostheses are found in Dentistry and Orthopaedy, such as dental implants, knee and hip articulation anchorages.The functionality and the average lifetime of such devices can be improved by the nitridation processes of titanium. The nitridation increases the mechanical strength and the chemical inertia and reduces the surface wear of the material.Thermal nitridations of Ti and Ti-6AI-4V alloys have been performed at temperatures between 300°C and 100 °C as a function of the time. Moreover, the ion implantation of nitrogen ions at 100-300 keV energy and high doses, up to about 107 ions/cm2, followed by thermal annealing at 500 °C, has been employed with success to reduce the surface wear and friction of movable prostheses and to increase their biocompatibility. Treated surfaces have been characterised by different physical analysis techniques, such as AES, XRD, RBS and SEM.

Endodontic instruments in NiTi alloy, useful in dentistry for restorative procedures, are investigated in terms of functionality, mechanical wear and temperature dependence. The instruments are studied by dynamical mechanical thermal analysis, differential scanning calorimetry, wear tests and scanning electron microscopy. The characterisation is given as a function of the temperature in the range between -30 °C and +80 °C. Obtained results point out the best conditions to use the files inside the dental root channels minimising the risk of their occasional rupture.

High-power pulsed lasers emitting IR and visible radiation with intensities ranging between 10^8 and 10^16 W/cm2, pulse duration from 0.4 to 9 ns and energy from 100 mJ up to 600 J, operating in single mode or in repetition rate, can be employed to produce non-equilibrium plasma in vacuum by irradiating solid targets. Such a laser-produced plasma generates highly charged and high-energy ions of various elements, as well as soft and hard X-ray radiations. Heavy ions with charge state up to 58+ and kinetic energy up to 10 MeV are detected. The plasma emits ion current densities of the order of tens of mA/cm^2. Interesting application possibilities of the generated plasmas concerning the ion implantation technique, the laser ion sources, the high intensity and resolution X-ray sources, the laser propulsion technique and the nuclear reaction of light elements are presented and discussed.

The Technical Reports are intended mainly for internal use within the COSMO group (COSMO = Consortium for Small Scale Modeling), but also to inform other groups on model changes and research activities. The purpose of the Technical Reports is 1. to document scientific research activities, 2. to document technical changes to the model system, 3. to give an overview on new components of the model system.

Effects of laser irradiation of Carbon nanotubes (CNTs) were investigated. Samples were laser-processed in different source conditions: pulsed laser beam of 248 nm, 532 nm and 1064 nm; pulse energy range from 100 mJ up to 500 mJ and shots number from 50 to 1800. Surface morphological changes and grain size distribution variations induced by the laser treatment were investigated through Scanning Electron Microscopy technique and counting software codes applied on the resulting images. Raman spectroscopy technique was employed for measurements of structural changes induced by the laser beam. Obtained results were compared with literature data about other carbon structures and irradiations conditions.

A summary of ion generation experiments at both low (10(9) W=cm²) and high (10(16) W=cm²) laser intensities, using Nd:YAG and iodine lasers, as well as the properties of the ions produced, are presented. Different medium- and high-Z elements were tested as a target: Ag, Al, Au, Co, Cu, Nb, Ni, Pb, Pt, Sn, Ta, W. A maximum charge state 55+ and maximum energy 34 MeV were recorded for Ta ions at high laser intensities, while the charge states up to 10+ and energies lower than 10 keV are characteristic for the region of low limit intensities. At laser intensities above 2 × 10(14) W=cm² conditions for the presence of nonlinear processes are fulfilled and ion acceleration due to ponderomotive force appears, in addition to the thermal and hot electron guided ambipolar acceleration. The existence of two production mechanisms for highly charged ions with charge states above z = 50+ has been demonstrated by changing the minimum focus position with regard to the target surface (by changing the interaction length with pre-formed plasma for relativistic self-focusing). Various potential applications of LIS are mentioned.