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High-energy heavy ion irradiation can produce permanent damage in the target material if the density of deposited energy surpasses a material-dependent threshold value. It is known that this threshold can be lowered in the vicinity of the surface or in the presence of defects. In the present study, we established threshold values for Al

High-energy heavy ion irradiation is a very useful tool for the nanostructuring of 2D materials because defects can be introduced in a controlled way. This approach is especially attractive for the mass production of graphene nanomembranes when nanopore size and density can easily be tuned by ion irradiation parameters such as ion energy and applied fluence. Therefore, understanding the basic mechanisms in nanopore formation due to high-energy heavy ion impact is of the highest importance. In the present work, we used Raman spectroscopy to investigate the response of bilayer and trilayer graphene to this type of irradiation. Spectra obtained from graphene samples irradiated with 1.8 MeV I, 23 MeV I, 3 MeV Cu, 18 MeV Cu, and 12 MeV Si beams were analysed using the Lucchese model. It was found that the efficiency of damage production scales strongly with nuclear energy loss. Therefore, even for the most energetic 23 MeV I beam, the electronic energy loss does not contribute much to damage formation and ion tracks are unlikely to be formed.

High energy ion irradiation is an important tool for nanoscale modification of materials. In the case of thin targets and 2D materials, which these energetic ions can pierce through, nanoscale modifications such as production of nanopores can open up pathways for new applications. However, materials modifications can be hindered because of subsequent energy release via electron emission. In this work, we follow energy dissipation after the impact of an energetic ion in thin graphite target using Geant4 code. Presented results show that significant amount of energy can be released from the target. Especially for thin targets and highest ion energies, almost 40% of deposited energy has been released. Therefore, retention of deposited energy can be significantly altered and this can profoundly affect ion track formation in thin targets. This finding could also have broader implications for radiation hardness of other nanomaterials such as nanowires and nanoparticles.

Both silicon and graphite are radiation hard materials with respect to swift heavy ions like fission fragments and cosmic rays. Recrystallisation is considered to be the main mechanism of prompt damage anneal in these two materials, resulting in negligible amounts of damage produced, even when exposed to high ion fluences. In this work we present evidence that these two materials could be susceptible to swift heavy ion irradiation effects even at low energies. In the case of silicon, ion channeling and electron microscopy measurements reveal significant recovery of pre-existing defects when exposed to a swift heavy ion beam. In the case of graphite, by using ion channeling, Raman spectroscopy and atomic force microscopy, we found that the surface of the material is more prone to irradiation damage than the bulk.

International audience; Nanopatterned surfaces play a key role for many applications exploiting unique features such as an enhanced surface area, long- and short-ranged morphology modulations or a spatial variation of electronic and chemical properties. Ion beam irradiation has been frequently used for nanostructuring bulk materials because it is efficient, fast, and cost-effective. In this paper we show that ion irradiation under extremely grazing incidence in conjunction with other scalable processing methods such as wet etching and thermal annealing, is a perfect tool for nanopatterning of dielectric surfaces. We demonstrate that by tuning ion energy and fluence, one can select different surface nanopattern morphologies like individual chains of nanohillocks, nanostripes, or nanoscaled ripples. Furthermore, chemical etching of the irradiated surface can be used to create a negative replica of the nanopattern as only the material making up the surface track is susceptible to the etching process and is thus removed. Also, a removal of the surface track can be achieved by thermal annealing in vacuum. All these presented strategies open up new ways for achieving control over nanoscale surface modifications using swift heavy ion beams.

We experimentally discovered that Al2O3 and MgO exhibit well-pronounced nanometric modifications on the surfaces when irradiated under grazing incidence with 23 MeV I beam, in contrast to normal incidence irradiation with the same ion beam when no damage was found. Moreover, ions in these two materials produce notably different structures: grooves surrounded with nanohillocks on MgO surfaces vs. smoother, roll-like discontinuous structures on the surfaces of Al2O3. To explain these results, detailed numerical simulations were performed. We identified that a presence of the surface inhibits recrystallization process, thereby preventing transient tracks from recovery, and thus forming observable nanopatterns. Furthermore, a difference in the viscosities in molten states in Al2O3 vs. MgO explains the differences in the created nanostructures. Our results thus provide a deeper understanding of the fundamental processes of surface nanostructuring, potentially allowing for controlled production of periodic surface nanopatterns.

The hexagonal silicon carbide (6H-SiC) is one of materials used in nuclear applications, and as such is exposed to crystal damage inducing by variety of energetic particles like neutrons. In this article the 6H-SiC crystal lattice damage was introduced by the 4 MeV C3+ and 4 MeV Si3+ channelling ion implantation at the room temperature. The implantation of C and Si ions (so called self-ions) to the set of different fluences, achieves a 6H-SiC crystal lattice damage more similar to what the exposure to neutrons would produce. The 6H-SiC crystal damage has been investigated by the Elastic Backscattering spectra taken in the channeling orientation (EBS/C). EBS/C spectra of the implanted 6H-SiC samples were taken with 1.725 MeV and 1.860 MeV protons. By fitting the EBS/C spectra, the quantitative 6H-SiC crystal damage depth profiles were obtained. Further, the cross section of crystal's implanted region has been scanned with the micro-Raman (μR) technique for a comparison. In this way, the qualitative analysis of a non-crystalline phase as a function of the crystal depth was independently determined. Additionally, a scanning electron microscopy (SEM) image was taken of the implanted crystal cross sections. The comparison of the crystal damage profiles obtained by fitting EBS/C spectra with the corresponding ones obtained with the μR and SEM techniques shows very good consistency between them.

Ion track formation in amorphous SiO2 was investigated using infrared spectroscopy. For comparison, one set of samples was also irradiated using 1.25 MeV gamma rays. An increase of 1044 cm−1 peak and decrease of 1078 cm−1 peak was observed in all cases. Experimental results were analysed using an analytical thermal spike model and non-standard model parameters were found. This finding is attributed to the amorphous structure of the material.

This article has an erratum: DOI 10.1016/j.carbon.2017.03.065 We examine swift heavy ion-induced defect production in suspended single layer graphene using Raman spectroscopy and a two temperature molecular dynamics model that couples the ionic and electronic subsystems. We show that an increase in the electronic stopping power of the ion results in an increase in the size of the pore-type defects, with a defect formation threshold at 1.22–1.48 keV/layer. We also report calculations of the specific electronic heat capacity of graphene with different chemical potentials and discuss the electronic thermal conductivity of graphene at high electronic temperatures, suggesting a value in the range of 1 Wm−1 K−1. These results indicate that swift heavy ions can create nanopores in graphene, and that their size can be tuned between 1 and 4 nm diameter by choosing a suitable stopping power.

Self-assembly of colloidal monolayers represents a prominent approach to the fabrication of nanostructures. The modification of the shape of colloidal particles is essential in order to enrich the variety of attainable patterns which would be limited by the typical assembly of spherical particles in a hexagonal arrangement. Polymer particles are particularly promising in this sense. In this article, we investigate the deformation of closely-packed polystyrene particles under MeV oxygen ion irradiation at normal incidence using atomic force microscopy (AFM). By developing a procedure based on the fitting of particle topography with quadrics, we reveal a scenario of deformation more complex than the one observed in previous studies for silica particles, where several phenomena, including ion hammering, sputtering, chemical modifications, can intervene in determining the final shape due to the specific irradiation conditions. In particular, deformation into an ellipsoidal shape is accompanied by shrinkage and polymer redistribution with the presence of necks between particles for increasing ion fluence. In addition to casting light on particle irradiation in a regime not yet explored, we present an effective method for the characterization of the colloidal particle morphology which can be applied to describe and understand particle deformation in other regimes of irradiation or with different techniques., Nanoletters, 10 (3), ISSN:2079-4991

A 6H-SiC single crystal implanted in channeling mode by 4-MeV C+3 and Si+3 ions at various doping levels has been examined by scanning electron microscopy (SEM) and micro-Raman spectroscopy in order to study the lattice distortions inflicted by the impinging ions. C ions create zones of strongly damaged regions, parallel to the front face of the wafer with width increasing with the amount of doping. As expected, Si has induced considerably more lattice distortions than C, and more than one order of magnitude less doping induces apparently the same effect as C. Despite the large laser spot size compared with the boundaries of the distorted regions, micro-Raman data provided results agreeing with the SEM pictures and the Monte Carlo calculations using the SRIM-2013 software. From the evolution of the crystalline peaks in the Raman spectra obtained across the damaged area, one can conclude that the impinging ions do not accommodate as defects in the lattice but mostly displace the ions breaking the bonds and destroying the long range order. The spatial correlation model that takes into consideration the intensity variation at the laser spot and the anticipated from Monte Carlo calculations for the collision events can reproduce the trend of the strong transversal optical phonon width indicating nanocrystallites of a few nanometers size in the most damaged area. © 2019 John Wiley & Sons, Ltd.

Simple and efficient methods for the accurate structural characterization of ion-beam modified materials are important due to their interesting properties and many applications. Here we demonstrate the application of the Grazing incidence small angle X-ray scattering (GISAXS) method on the structural analysis of swift heavy ion-beam modified materials. Passing through a material, an accelerated ion usually modifies its surrounding causing the formation of nano-objects along its trajectory, called ion track. We show that GISAXS can be used to determine the structural properties of the nano-objects formed along the ion tracks, as well as their ordering properties. We have developed theoretical models describing GISAXS intensity distributions of the systems having different ordering types. The efficiencies of the models are tested on experimental examples.

Highly ordered pyrolytic graphite and graphene created via chemical vapor deposition have been irradiated with high energetic I6+ ions. By Raman mapping an increase of the ID/IG ratio could be identified which arises from the ion induced defects. This ratio grows with increasing fluence. Using this as a tool, HOPG and graphene can be utilized to determine the ion beam spot size and its homogeneity. Both systems seem to be suitable for size determination of the spot. But due to the much higher sensitivity of graphene to ion irradiation, more detailed information regarding the homogeneity of the beam can only be derived using this 2D system. By comparison of both systems we conclude, that CVD graphene is more suitable as an ion beam detector, while HOPG is sufficient for a rough spot size analysis.

International audience; Conditions for ion track formation in single crystal SrTiO3 and TiO2 (rutile) after irradiations using swift heavy ion beams with specific energies below 1 MeV/amu were investigated in this work. Rutherford backscattering spectroscopy in channeling was used to measure ion tracks in the bulk, while atomic force microscopy was used for observation of ion tracks on the surfaces. Variations in the ion track sizes and respective thresholds were observed after irradiations under random, channeling and near-channeling conditions close to normal incidence. These variations are attributed to the specifics of the electronic stopping power of swift heavy ions under the investigated conditions. In the case of ion channeling, electronic stopping power is reduced and observed ion tracks are smaller. The opposite was found under the near-channeling conditions when lowering of the ion track formation threshold was observed. We attribute this finding to the oscillating electronic stopping power with large peak values. For both materials, thresholds for bulk and surface ion track formation were found to be surprisingly close, around 10 keV nm−1. Obtained results are compared with predictions of the analytical thermal spike model.

There is ongoing debate regarding the mechanism of swift heavy ion track formation in CaF2. The objective of this study is to shed light on this important topic using a range of complimentary experimental techniques. Evidence of the threshold for ion track formation being below 3 keV/nm is provided by both transmission electron microscopy and Rutherford backscattering spectroscopy in the channeling mode which has direct consequences for the validity of models describing the response of CaF2 to swift heavy ion irradiation. Advances in the TEM and RBS/c analyses presented here pave the way for better understanding of the ion track formation., full paper

The aim of this work is to investigate the feasibility of ion beam analysis techniques for monitoring swift heavy ion track formation. First, the use of the in situ Rutherford backscattering spectrometry in channeling mode to observe damage build-up in quartz SiO#8322; after MeV heavy ion irradiation is demonstrated. Second, new results of the in situ grazing incidence time-of-flight elastic recoil detection analysis used for monitoring the surface elemental composition during ion tracks formation in various materials are presented. Ion tracks were found on SrTiO#8323;, quartz SiO#8322;, a-SiO#8322;, and muscovite mica surfaces by atomic force microscopy, but in contrast to our previous studies on GaN and TiO#8322;, surface stoichiometry remained unchanged. Third, the usability of high resolution particle induced X-ray spectroscopy for observation of electronic dynamics during early stages of ion track formation is shown.

Irradiation of materials by heavy ions accelerated in MV tandem accelerators may lead to the production of latent ion tracks in many insulators and semiconductors. If irradiation is performed in a high resolution microprobe facility, ion tracks can be ordered by submicrometer positioning precision. However, full control of the ion track positioning can only be achieved by a reliable ion hit detection system that should provide a trigger signal irrespectively of the type and thickness of the material being irradiated. The most useful process that can be utilised for this purpose is emission of secondary electrons from the sample surface that follows the ion impact. The status report of the set-up presented here is based on the use of a channel electron multiplier (CEM) detector mounted on an interchangable sample holder that is inserted into the chamber in a close geometry along with the sample to be irradiated. The set-up has been tested at the Zagreb ion microprobe for different ions and energies, as well as different geometrical arrangements. For energies of heavy ions below 1 MeV/amu, results show that efficient (100%) control of ion impact can be achieved only for ions heavier than silicon. The successful use of the set-up is demonstrated by production of ordered single ion tracks in a polycarbonate film and by monitoring fluence during ion microbeam patterning of Foturan glass.

Formation of ion tracks on a rutile TiO2 (001) surface after exposure to swift heavy ions under grazing incidence is studied using atomic force microscopy, grazing-incidence small-angle X-ray scattering and in situ time-of-flight elastic recoil detection analysis., Nanostructuring of surfaces and two-dimensional materials using swift heavy ions offers some unique possibilities owing to the deposition of a large amount of energy localized within a nanoscale volume surrounding the ion trajectory. To fully exploit this feature, the morphology of nanostructures formed after ion impact has to be known in detail. In the present work the response of a rutile TiO2 (001) surface to grazing-incidence swift heavy ion irradiation is investigated. Surface ion tracks with the well known intermittent inner structure were successfully produced using 23 MeV I ions. Samples irradiated with different ion fluences were investigated using atomic force microscopy and grazing-incidence small-angle X-ray scattering. With these two complementary approaches, a detailed description of the swift heavy ion impact sites, i.e. the ion tracks on the surface, can be obtained even for the case of multiple ion track overlap. In addition to the structural investigation of surface ion tracks, the change in stoichiometry of the rutile TiO2 (001) surface during swift heavy ion irradiation was monitored using in situ time-of-flight elastic recoil detection analysis, and a preferential loss of oxygen was found.

In the present work we investigate effects ofMeVheavy ions (from 0.4 MeVXe to 15 MeVSi) on regularly ordered nanoparticle (NP) lattices embedded in amorphous alumina matrix. These nanostructures were produced by self-assembling growth using magnetron-sputtering deposition. From grazing incidence small-angle x-ray scattering measurements we have found that the usedMeV heavy ions do not change the NPsizes, shapes or distances among them. However, ions cause a tilt of the entire NP lattice in the direction parallel to the surface. The tilt angle depends on the incident ion energy, type and the applied fluence and a nearly linear increase of the tilt angle with the ion fluency and irradiation angle was found. This way,MeV heavy ion irradiation can be used to design custom-made NPlattices. In addition, grazing incidence small-angle x-ray scattering can be effectively used as a method for the determination of material redistribution/shift caused by the ion hammering effect. For the first time, the deformation yield in amorphous alumina was determined for irradiation performed at the room temperature. Iva Bogdanovic Radovic

Nanostructuring of surfaces and two-dimensional materials using swift heavy ions offers some unique possibilities owing to the deposition of a large amount of energy localized within a nanoscale volume surrounding the ion trajectory. To fully exploit this feature, the morphology of nanostructures formed after ion impact has to be known in detail. In the present work the response of a rutile TiO2 (001) surface to grazing-incidence swift heavy ion irradiation is investigated. Surface ion tracks with the well known intermittent inner structure were successfully produced using 23 MeV I ions. Samples irradiated with different ion fluences were investigated using atomic force microscopy and grazing-incidence small-angle X-ray scattering. With these two complementary approaches, a detailed description of the swift heavy ion impact sites, i.e. the ion tracks on the surface, can be obtained even for the case of multiple ion track overlap. In addition to the structural investigation of surface ion tracks, the change in stoichiometry of the rutile TiO2 (001) surface during swift heavy ion irradiation was monitored using in situ time-of-flight elastic recoil detection analysis, and a preferential loss of oxygen was found.

The installation of a new 1.0 MV Tandetron accelerator and a recent upgrade of the 6.0 MV Tandem Van de Graaff accelerator increased the application possibilities of the Zagreb ion microbeam system. Several ion sources enable now the selection of a wide variety of ions. Most of them can be focused by the existing microprobe system. Sample positioning tools and new scanner control options are implemented in the new generation of SPECTOR data acquisition system. Details of the upgrades are presented.

International audience; We investigated the response of wurzite GaN thin films to energetic ion irradiation. Both swift heavy ions (92 MeV Xe23+, 23 MeV I6+) and highly charged ions (100 keV Xe40+) wereused. After irradiation, the samples were investigated using atomic force microscopy, grazing incidence small angle x-ray scattering, Rutherford backscattering spectroscopy in channelling orientation and time of flight elastic recoil detection analysis. Only grazing incidence swift heavy ion irradiation induced changes on the surface of the GaN, when the appearance of nanoholes is accompanied by a notable loss of nitrogen. The results are discussed in the framework of the thermal spike model.

The ability to manufacture tailored graphene nanostructures is a key factor to fully exploit its enormous technological potential. We have investigated nanostructures created in graphene by swift heavy ion induced folding. For our experiments, single layers of graphene exfoliated on various substrates and freestanding graphene have been irradiated and analyzed by atomic force and high resolution transmission electron microscopy as well as Raman spectroscopy. We show that the dense electronic excitation in the wake of the traversing ion yields characteristic nanostructures each of which may be fabricated by choosing the proper irradiation conditions. These nanostructures include unique morphologies such as closed bilayer edges with a given chirality or nanopores within supported as well as freestanding graphene. The length and orientation of the nanopore, and thus of the associated closed bilayer edge, may be simply controlled by the direction of the incoming ion beam. In freestanding graphene, swift heavy ion irradiation induces extremely small openings, offering the possibility to perforate graphene membranes in a controlled way., Comment: 16 pages, 5 figures, submitted to Nanotechnology

Examples and opportunities for technology transfer at RBI accelerator facility

In this article, we show how to produce materials consisting of regularly ordered Ge quantum dot lattices in an amorphous alumina matrix with a controllable Ge quantum dot size, shape, spacing, crystalline structure, and degree of regularity in their ordering. The production of such materials is achievable already at room temperature by magnetron sputtering deposition of a (Ge + Al2O3)/Al2O3 multilayer. The materials show photoluminescence in the visible and ultraviolet light range, a size-dependent blue shift of the photoluminescence peak and an enhancement of its intensity by size reduction, indicating the quantum dot origin of the photoluminescence. The materials also exhibit excellent mechanical properties due to the alumina matrix. Their internal structure is shown to be highly resistive to irradiation with energetic particles for a large range of the irradiation parameters.

Materials modifications using swift heavy ion beams provided by large scale accelerators have been used for many years in a wide variety of ways, e.g. to produce ion tracks or to modify the shape of nanoparticles. In all those applications the most relevant parameter for the materials modification is the electronic stopping power and not the ion kinetic energy. For many materials, ions with energies below 1 MeV/u delivered from medium and small size accelerators have already sufficiently high electronic stopping power to modify materials in different ways. Also, in this energy range the nuclear stopping power can be large enough to provide additional opportunities for materials modifications. In the present paper, we review recent experimental activities of the Zagreb group where ion beams with energies below 1 MeV/u, obtained from a 6 MV EN Tandem Van de Graaff accelerator have been used. Additionally, we present several novel examples of materials modifications and their analysis with such ion beams.

We investigate how MeV ions with different ion-beam parameters (ion type, electronic stopping power, and velocity) influence the formation, arrangement, and ordering quality in three types of ($\mathrm{Ge}+{\mathrm{SiO}}_{2})/{\mathrm{SiO}}_{2}$ multilayer films. The multilayers differ in total thickness, Ge-rich layer thickness, and Ge content. The results show that the most important parameter for structural manipulation with MeV ions is the electronic stopping power ${S}_{e}$. Ion velocity is found to be another crucial parameter, while at the same time it can be seen that the multilayer type does not play an important role. The temperature increase within the ion tracks is estimated using the thermal spike model and cluster separation distribution. The structural changes produced by ion beams and estimated temperatures are compared to those obtained by standard thermal annealing. It is concluded that the estimated temperatures within the ion tracks are in excellent agreement with the annealing temperatures and with the structural changes observed in the irradiated multilayers. Furthermore, a characteristic parameter of the temperature profile that presents the model-predicted temperature increase is determined for which the structural changes caused by ion beams are comparable to those achieved by standard annealing.

We report on a method for the determination of ion track radii, formed in amorphous materials by ion- beam irradiation. The method is based on the addition to an amorphous matrix of a small amount of foreign atoms, which easily diffuse and form clusters when the temperature is sufficiently increased. The irradiation causes clustering of these atoms, and the final separations of the formed clusters are dependent on the parameters of the ion-beam. Comparison of the separations between the clusters that are formed by ions with different properties in the same type of material enables the determination of ion-track radii.

The irradiation of material using swift heavy ion or highly charged ion causes excitation of the electron subsystem at nanometer scale along the ion trajectory. According to the thermal spike model, energy deposited into the electron subsystem leads to temperature increase due to electron–phonon coupling. If ion-induced excitation is sufficiently intensive, then melting of the material can occur, and permanent damage (i.e., ion track) can be formed upon rapid cooling. We present an extension of the analytical thermal spike model of Szenes for the analysis of surface ion track produced after the impact of highly charged ion. By applying the model to existing experimental data, more than 60% of the potential energy of the highly charged ion was shown to be retained in the material during the impact and transformed into the energy of the thermal spike. This value is much higher than 20–40% of the transferred energy into the thermal spike by swift heavy ion. Thresholds for formation of highly charged ion track in different materials show uniform behavior depending only on few material parameters.

Iron films were deposited onto the Si (100) substrates by DC-magnetron sputtering and subsequently annealed in the temperature range of 873 K to 1273 K for 2 hours. Rutherford backscattering analysis was performed to determine the elemental depth profiles and the oxidation process in samples. The silicides formation was characterized by X-ray diffraction. The results indicate that annealing at 873 K causes only a small mixing of the Fe and Si atoms near the Fe/Si interface, while the 973 K annealing enhances the atomic diffusion and yields to a graded concentration distribution of Fe and Si. The metal-rich silicides Fe1+xSi (0≤x≤2) start to nucleate and grow at 973 K and only α - FeSi2 formation is conduced after annealing at 1273 K for 2 hours.

We studied the generation of an ordered Ge quantum dot array in an amorphous silica matrix by ion beam irradiation. In particular we investigated the influence of the irradiation process on the nucleation of Ge clusters, on the correlations in their positions and on the crystalline quality of Ge quantum dots formed after subsequent annealing. We have developed a method for the description of the intensity of grazing-incidence x-ray small-angle scattering from irradiated multilayers, which enables a precise determination of the arrangement of quantum dots as well as their position correlation and size distribution. The analysis shows that the irradiation causes an ordering of Ge clusters along the irradiation direction, which substantially improves the correlations of the Ge dot locations in their three-dimensional array. The observed phenomena are explained and simulated by a Monte Carlo model based on the modification of local Ge density induced by ion tracks in the irradia! ted multilayers.

A two-step procedure for the formation of silver nanoparticles embedded in a glass matrix is studied. The procedure consists of: (i) the inclusion of silver ions in the glass matrix by electric field assisted dissolution of Ag film deposited on the glass and (ii) the aggregation of silver by thermal annealing. The optical properties of the sample, dominated by the surface plasmon resonance of metal nanoparticles in the visible spectral range, are studied by optical spectroscopy. The structural characterization is carried out by grazing-incidence small-angle X-ray scattering measurements performed at the Synchrotron Elettra (Italy) and silver depth profiles are determined using Rutherford backscattering. The results suggest that the depth profile of Ag might be tailored by modification of the parameters of metal film dissolution (electric field and temperature). Variation of thermal annealing parameters (temperature and time) allows control of the nanoparticles size. Thus, the surface plasmon absorption intensity and line shape are changed, enabling tuning of the optical properties of the sample.

We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation.

Study of bactericidal effect of silver nanoparticles (AgNPs), free of chemical byproducts, could be of great importance in understanding the underlying antibacterial mechanism(s). In this work, we present the production and characterization of AgNPs, synthesized by laser ablation of silver in water, and optical density (OD) growth curves of E. coli cells treated at sub MIC (minimal inhibitory concentration) and MIC concentrations. Besides the increase of the baseline and reduction of the maximal OD, the main impact of the treatment is the increase of the lag time, which becomes infinitive for the MIC treatment. The obtained bacterial growth curves are described by a novel growth and inactivation model given by the set of three differential equations. Our model fits the OD data very well and explains the apparent lag phase, which we found to be a dynamic state in which the bacterial growth and death rates are close in value.

Generation of new laser profiles which are fully defined inside the resonator and require no additional optical shaping presents a challenging task but promise a viable route for use in particle confinement, laser tweezers, magneto-optical and gravito-optical traps, optoelectronics and in communication technology. Here we will show how both linear and cylindrical laser profiles have been realized and emphases their application. We used a laser resonator consisting of two mirrors, gain medium CdSe nanoparticle in solution, and an additional optical component placed within the resonator that is ultimately responsible for the shape of the output laser profile. This optical component proved to be the most challenging part of the setup since it had to be almost completely transparent in order to achieve a laser effect. For pump beam we used a 532 nm nanosecond laser and got the output laser emission at 655 nm. We additionally used similar setup to achieve a NOT logical gate which, due to the use of the nanoparticles in solution and not the standard semiconductor elements, present a unique realization of completely optical logic gate. We will show that besides the relatively trivial realization of AND and OR logic gates this setup could also be used to create XOR gates which then allows for realization of a complete optical logical algebra for possible application in information processing.

Al-doped ZnO and pure ZnO colloidal particles were synthesized by a pulsed laser ablation in water (laser ablation in liquids, LAL). Experiments were performed systematically by changing a variety of experimental conditions like target type (pure ZnO and ZnO doped with 2 wt. % of Al2O3), type of water (MilliQ and deionized water), number of applied laser pulses, laser output energy, and laser pulse wavelength with the aim to affect the particle size, their composition and band gap. The ZnO particles properties were studied using different techniques like grazing-incidence x- ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy and energy-dispersive x-ray spectroscopy. XRD patterns of formed particles show that for all experimental conditions correspond to ZnO. SEM investigation of colloidal particles revealed that the formed particles are 20-30 nm thick discs with diameter of 100-1400 nm. It is explained by efficient particle growth through diffusion process which take place in spatially restricted volume of the target crater. The diameter of the particles does not depend on any other experimental conditions except on type of water. When laser ablation takes place in deionized water synthesized particles have mesh-like structure with sparse number of disc- like particles. It is found that both absorbance and volume of ablated craters depend linearly on number of applied laser pulses and asymptotically on laser energy. It was found that LAL appeared as efficient and versatile technique for synthesis of ZnO and Al-doped ZnO nanoparticles.

1. Motivation. There is a continuous need for improved materials so they are more resistant or have some special properties, such as antibacterial and antimicrobial properties. However, various applications require materials that have one-off application and should therefore be economical and good for the environment. Such materials, that are inexpensive, are polymers and they have diverse applications, for a good part in medicine. Since one of the possible ways to improve a material is nanoparticle impregnation, this work presents three methods of nanoparticle impregnation into polymers. Preliminary research was done on different polymers with multiple colloidal nanoparticles, whereas a special attention was devoted to studies of PVC polymer and Au nanoparticles. 2. Experiment. Nanoparticles used in this experiment were in their colloidal form, synthesized within this research by a process of laser ablation. Laser synthesis of nanoparticles in liquids is known as the “green synthesis” technique as it provides not inhalable colloidal nanoparticles of wide variety of metals with no residues or byproducts, and often no further purification is required. Moreover, the laser pulses can additionally generate, de-agglomerate, fragmentate, and re-shape nanoparticles. In addition to those advantages, the laser ablation is a simple and straightforward technique and only a small piece of metal is needed for the process, with no unused remains. Unlike the methods where nanoparticles are incorporated not only at the surface but in the bulk of polymer material, our method is focused on incorporating nanoparticles only to the surface, keeping the bulk material untouched. This is a cost-efficient route to incorporate nanoparticles into polymers. Within this approach, 4 methods are tested: 1) Au nanoparticles deposited onto the polymer surface by drop-coating method, 2) polymer surface treated with APPJ, 3) polymer surface containing nanoparticles deposited by drop- coating on plasma pre-treated polymer, and 4) polymer surface containing nanoparticles deposited by drop-coating and sequent plasma treatment after water evaporated. 3. Results. The analysis of colloidal nanoparticles exhibits a narrow size distribution which is suitable for antibacterial applications. Moreover, the preliminary results of roughness and contact angle demonstrate appropriate change for nanoparticle impregnation on multiple polymers, especially PVC. SEM images show presence of Au nanoparticles on all samples, especially on a sample not treated with APPJ (just Au drop coating) since there, nanoparticles are present only on the surface. In samples where NPs are put first and then the polymer was treated with APPJ, NPs are harder to detect due to the increased surface roughness. 4. Conclusion. The presented work shows preliminary results of constructing antibacterial coatings. Some of the methods of nanoparticle impregnation, such as combinations of APPJ treatment with NPS, are promising.

In this work a cold atmospheric pressure plasma jet (APPJ) for sterilization and conservation of wooden artifacts is used. APPJ is rich of cold reactive species responsible for treatment of surfaces without thermal damage. Treatment of surfaces with APPJ can be performed on site either in interiors or exteriors/in open space. This research includes the application of a plasma jet for surface treatment of various wooden artifacts in terms of removing impurities and sterilization of microorganisms and worms, removing of subsequent interventions on the painted layer and, if it works, at some extent, it will complement standard techniques of desensitization/disinfection based on using hazardous chemicals, vacuum or gamma rays or using of chemical solvents for removing subsequent interventions. The goal of this work is to prove that this method for sterilization, disinfection of wooden artifacts and removing of subsequent interventions will work and can be applied to restoration and conservation of wooden artifacts. In this work we will show preliminary results on application of APPJ on artificially prepared paintings on wood including removal and change of morphology of surfaces. To some extent, APPJ is capable to remove and change of morphology of lacquer for wood while removal of paint layers as part of additional interventions is still a big issue. Further application of APPJ on sterilization and disinfection of wooden artifacts will be done.