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Abstract: The dependence of the precision of uranium isotope ratio on particle diameter in secondary ion mass spectrometry (SIMS) was investigated. Each uranium particle in certified reference materials with different isotopic composition (235U/238U=0.01–1.00) was observed with a scanning electron microscope (SEM) and transferred by a manipulator on a glassy-carbon planchet for subsequent isotope ratio analysis with SIMS. The relative standard deviation (RSD) of uranium isotope ratios varied with particle diameter, the amount of less abundant uranium isotope and the number of measurement cycles. For the particle with the diameter less than 1.0μm, the RSD significantly increased with increasing the number of measurement cycles, which is due to the difficulty of obtaining constant signals for a long duration. In contrast, no significant increase in the RSD was observed in the analysis of the particle with the diameter larger than 2.0μm. As the results, it is estimated that the 235U amount of 4.5fg is sufficient to obtain the 235U/238U ratio with the RSD within 5.0%. For the analysis of minor isotopes, the 234U amount of 0.42fg and the 236U amount of 1.1fg are sufficient to obtain the 234U/238U and 236U/238U ratios with the RSD within 20%, respectively. [Copyright &y& Elsevier]

Abstract: A novel TOF-SIMS apparatus was designed and constructed aiming at single small particle analysis. The apparatus consisted of high lateral resolution TOF-SIMS part and SEM function for seeking analytical target. A pulsed Ga-focused ion beam (FIB) was also newly developed for this purpose based on state-of-the art ion optics. Secondary ion yield of Al was 1.8×10−2 which is high enough small area analysis, and mass resolution was also acceptable for element analysis. The most prominent feature, lateral resolution, was demonstrated to be 40nm in actual mapping of an IC cross-section. As an application aerosol particles were analyzed individually. [Copyright &y& Elsevier]

Abstract: Hydrodynamic simulations are used to evaluate the potential of ultrashort laser pulses to localize energy at metallic surfaces, in our case aluminum. The emphasis is put on the dynamic sequence of laser energy deposition steps during the electron–ion nonequilibrium stage and the subsequent matter transformation phases. The simulations indicate correlated optical and thermodynamical states associated to specific electronic collisional mechanisms. The timescales of energy deposition deliver a guideline for using relevant relaxation times to improve the energy coupling into the material. We focus on a class of pump-probe experiments which investigate energy storage and particle emission from solids under ultrafast laser irradiation. Moreover, we have used our model to explain the experimentally observed optimization of energy coupling by tailoring temporal laser intensity envelopes and its subsequent influence on the ablation rate and on the composition of ablation products. Potential control for nanoparticle generation is discussed. [Copyright &y& Elsevier]

Abstract: The ELI (Extreme Light Infrastructure) Beamlines facility in the Czech Republic, which is planned to complete the installation in 2015, is one of the four pillars of the ELI European project. Several laser beamlines with ultrahigh intensities and ultrashort pulses are foreseen, offering versatile radiation sources in an unprecedented energy range: laser-driven particle beams are expected to range between 1 and 50GeV for electrons and from 100MeV up to 3GeV for protons. The number of particles delivered per laser shot is estimated to be 109–1010 for the electron beams and 1010–1012 for the proton beams. The high energy and current values of the produced particles, together with the potentiality to operate at 10Hz laser repetition rate, require an accurate study of the primary and secondary radiation fields to optimize appropriate shielding solutions: this is a key issue to minimize prompt and residual doses in order to protect the personnel, reduce the radiation damage of electronic devices and avoid strong limitations in the operational time. A general shielding study for the 10PW (0.016Hz) and 2PW (10Hz) laser beamlines is presented here. Starting from analytical calculations, as well as from dedicated simulations, the main electron and proton fields produced in the laser-matter interaction have been described and used to characterize the “source terms” in full simulations with the Monte Carlo code FLUKA. The secondary radiation fields have been then analyzed to assess a proper shielding. The results of this study and the proposed solutions for the beam dumps of the high energy beamlines, together with a cross-check analysis performed with the Monte Carlo code GEANT4, are presented. [Copyright &y& Elsevier]

Abstract: The morphology, chemical composition, and mechanical properties in the surface region of α-irradiated polytetrafluoroethylene (PTFE) have been examined and compared to unirradiated specimens. Samples were irradiated with 5.5MeV 4He2+ ions from a tandem accelerator to doses between 1×106 and 5×1010 Rad. Static time-of-flight secondary ion mass spectrometry (ToF-SIMS), using a 20keV C60 + source, was employed to probe chemical changes as a function of α dose. Chemical images and high resolution spectra were collected and analyzed to reveal the effects of α particle radiation on the chemical structure. Residual gas analysis (RGA) was utilized to monitor the evolution of volatile species during vacuum irradiation of the samples. Scanning electron microscopy (SEM) was used to observe the morphological variation of samples with increasing α particle dose, and nanoindentation was engaged to determine the hardness and elastic modulus as a function of α dose. The data show that PTFE nominally retains its innate chemical structure and morphology at α doses <109 Rad. At α doses ≥109 Rad the polymer matrix experiences increased chemical degradation and morphological roughening which are accompanied by increased hardness and declining elasticity. At α doses >1010 Rad the polymer matrix suffers severe chemical degradation and material loss. Chemical degradation is observed in ToF-SIMS by detection of ions that are indicative of fragmentation, unsaturation, and functionalization of molecules in the PTFE matrix. The mass spectra also expose the subtle trends of crosslinking within the α-irradiated polymer matrix. ToF-SIMS images support the assertion that chemical degradation is the result of α particle irradiation and show morphological roughening of the sample with increased α dose. High resolution SEM images more clearly illustrate the morphological roughening and the mass loss that accompanies high doses of α particles. RGA confirms the supposition that the outcome of chemical degradation in the PTFE matrix with continuing irradiation is evolution of volatile species resulting in morphological roughening and mass loss. Finally, we reveal and discuss relationships between chemical structure and mechanical properties such as hardness and elastic modulus. [Copyright &y& Elsevier]

Abstract: In this study, we attempted to characterize environmental nanoparticles and particle diameter distributions in the atmospheric environment neighboring a traffic route by using a scanning mobility particle sizer (SMPS). The composition of the environmental nanoparticles was analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). It was observed that the environmental nanoparticles showed peaks at 20nm and 100nm. The secondary ions C+, O+, Si+, and SiH3 + were strongly detected in the environmental nanoparticles with a peak at 20nm. On the other hand, the secondary ions NH4 +, Na+, K+, and Ca+ were detected in the environmental nanoparticles with a peak at 100nm. Moreover, it was found that the secondary ion spectral patterns of the organic compounds were different for each particle diameter. Hence, we concluded that the combination of the SMPS with TOF-SIMS is a powerful technique to characterize environmental nanoparticles. [Copyright &y& Elsevier]

Abstract: The origins of carrier particles of complex particles (iron-rich particles) collected from the urban atmospheric environment near to road traffic and a railroad were investigated from the detailed surface information using FE-SEM/EDS and TOF-SIMS analyses. From the FE-SEM/EDS analyses, the iron-rich particles were classified into two typical types (spherical type and non-spherical type). From the TOF-SIMS measurements, the characteristic secondary ions of spherical type of iron-rich particles were 23Na+ and 39K+. The minor components of non-spherical type were Al, Ca and Ba. On the other hand, we carried out TOF-SIMS measurement to materials of rail origin and brake origin. From the comparison of these spectra pattern, it seemed that the spherical type of iron-rich particles was emitted from the rail origin. We concluded that the origin of non-spherical type of iron-rich particles were brake pad of vehicles. [Copyright &y& Elsevier]

Abstract: A combination of micro-analytical techniques was used for the characterization of spherical particles in the size range 9–12μm as a part of nuclear safeguards verification activities pursuant to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). The particles were removed from cotton swipe samples taken in a nuclear facility under safeguards and examined first by scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM–EDX). Particles of interest were then relocated under an optical microscope and manipulated. One such particle was subjected to destructive analysis by secondary ion mass spectrometry (SIMS) in order to determine if uranium was present in the core of the particle. A second particle was examined using focused ion beam (FIB) etching to allow an examination of the interior by SEM–EDX. The particle manipulation and relocation techniques presented here allow the sequential examination of a single particle of interest by a combination of analytical techniques, thus yielding surface morphological, elemental, isotopic and depth-profiling information. The objective of these investigations is to provide assurance of the absence of clandestine or undeclared nuclear activities in States coming under comprehensive safeguards obligations. [Copyright &y& Elsevier]

Abstract: Local charge neutralization using secondary electrons generated by an electron beam (EB) for SEM was devised and examined. Neutralization with a high-energy EB compared with conventional very low-energy EB requires no pulsing scheme for TOF-MS extraction voltage. Direct irradiation of high-energy EB to the insulating particle was not effective for neutralization. It was shown that the use of secondary electrons induced by EB-irradiation not on the particle directly but on a metal substrate vicinity of the particle. Charge neutralization was found to be effective even when the EB spot was distant (60μm). [Copyright &y& Elsevier]

Abstract: Coatings formed on 2024-T3 aluminum alloy were studied by scanning electron microscopy (SEM) and scanning Auger microscopy (SAM) after dipping in zinc phosphating (ZPO) baths at different acidities, with or without the Ni2+ additive. The objective was to learn more about the ZPO coating mechanism on the different microstructural regions of 2024-T3. When the initial coating solution pH is 4 (optimal acidity), a slower etching rate at the Al–Cu–Fe–Mn intermetallic particle causes significant precipitation of ZnO, which differs from the coating on other regions of the surface where phosphate predominates. The larger crystals (∼μm dimension) on the matrix and the Al–Cu–Mg particle contain more phosphate compared to other areas on the surface. When Ni2+ is added to the coating solution, the Al–Cu–Mg particle is more thickly coated compared to when the Ni2+ is not present. The slower rate of precipitation when Ni2+ is present in the coating solution increases the exposure of the alloy substrate to the acidic environment, so allowing more dissolution of Mg and Al from the Al–Cu–Mg particle. This results in the particle becoming more cathodic in nature, and therefore more coating deposits at this location. Evidence from SAM supports the presence of NiAl2O4, hypothesized in Part I, forming at coating pores later in the process. [Copyright &y& Elsevier]

Abstract: The impact of ultra-short laser pulses induces intensity-dependent non-equilibrium processes in the surface region of dielectric targets, resulting in desorption of surface constituents. We report time-resolved studies on particle ejection from CaF2 and BaF2 targets. Pump–probe time-of-flight mass spectrometry (ToF MS) was used to measure the particle yields as a function of the delay time between pairs of sub-damage threshold laser pulses, thus obtaining the temporal dynamics of the laser-excited charged particle emission. In a correlative manner, the positive ion, electron and negative ion desorption yields dependence on the pump–probe delay time reveal a coherence peak around zero delay (similar to a two-pulse autocorrelation), accounting for the increase of the ion yield with laser intensity. Additionally, the measurements reveal a delayed peaks at ∼900fs (BaF2) and ∼300fs (CaF2). For comparison, we present time-resolved studies on electron emission from aluminum targets with pump and probe pulses below the damage threshold. The measurements show, again, the autocorrelation peak in the coherence region and an additional increase in the electron yield when the pulses are several picoseconds apart. The autocorrelation could also stand for the dephasing time of the electronic coherence, while the delayed peaks may reveal for the time needed for the collisional energy to be transferred to the lattice. The pump pulse induces a new unstable phase, which is further destabilized by the probe pulse. A corresponding qualitative picture for temporal dynamics of femtosecond (fs) laser-induced particle emission is proposed. [Copyright &y& Elsevier]

Abstract: Recently, we have developed a new tight-binding quantum chemical molecular dynamics program “Colors” for combinatorial computational chemistry approach. This methodology is based on our original tight-binding approximation and realized over 5000 times acceleration compared to the conventional first-principles molecular dynamics method. In the present study, we applied our new program to the simulations on various realistic large-scale models of the automotive three-way catalysts, ultrafine Pt particle/CeO2(111) support. Significant electron transfer from the Pt particle to the CeO2(111) surface was observed and it was found to strongly depend on the size of the Pt particle. Furthermore, our simulation results suggest that the reduction of the Ce atom due to the electron transfer from the Pt particle to the CeO2 surface is a main reason for the strong interaction of the Pt particle and CeO2(111) support. [Copyright &y& Elsevier]

Abstract: Studies were presented on production of highly dispersed magnesium silicate at a pilote scale. The process of silicate adsorbent production involved precipitation reaction using water glass (sodium metasilicate) solution and appropriate magnesium salt, preceded by an appropriate optimization stage. Samples of best physicochemical parameters were in addition modified (in order to introduce to silica surface of several functional groups) using the dry technique and various amounts of 3-isocyanatepropyltrimethoxysilane, 3-thiocyanatepropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane. The so prepared samples were subjected to a comprehensive physicochemical analysis. At the terminal stage of studies attempts were made to adsorb phenol from its aqueous solutions on the surface of unmodified and modified magnesium silicates. Particle size distributions were determined using the ZetaSizer Nano ZS apparatus. In order to define adsorptive properties of studied magnesium silicates isotherms of nitrogen adsorption/desorption on their surfaces were established. Efficiency of phenol adsorption was tested employing analysis of post-adsorption solution. [Copyright &y& Elsevier]

Abstract: The size, shape and surface topology have a strong influence on powders properties, such as: mechanical, optical, catalytic, etc. In addition, when particles have a nanometer size, the dispersion of these features plays an important role. There are a number of techniques, which could be used in order to characterize powders in terms of particle size and shape. However, due to the scale of analysis, well beyond the wavelength of visible light, most of them cannot be applied for investigations of nanopowders. In this paper, transmission electron microscopy (TEM) image analysis and X-ray methods are presented as promising and complementary techniques. An example of their application to ZrO2 nanopowder is shown. The advantages and limitations of each method are described. [Copyright &y& Elsevier]

In particle accelerators with intense positively charged bunched beams, an electron cloud may induce beam instabilities and the related beam induced electron multipacting (BIEM) can result in an undesired pressure rise. In a cryogenic machine such as the large hadron collider (LHC), the BIEM will introduce additional heat load. When present, synchrotron radiation (SR) may generate a significant number of photoelectrons, that may play a role in determining the onset and the detailed properties of the electron cloud related instability. Since electrons are constrained to move along field lines, those created on the accelerator equator in a strong vertical (dipole) field cannot participate in the e-cloud build-up. Therefore, for the LHC there has been a continuous effort to find solutions to absorb the photons on the equator. The solution adopted for the LHC dipole beam screens is a saw-tooth structure on the illuminated equator. SR from a bending magnet beamline at ELETTRA, Italy (BEAR) has been used to measure the reflectivities (forward, back-scattered and diffuse), for a flat and a saw-tooth structured Cu co-laminated surface using both white light SR, similar to the one emitted by LHC, and monochromatic light. Our data show that the saw-tooth structure does reduce the total reflectivity and modifies the photon energy distribution of the reflected photons. The implications of these results on the LHC arc vacuum system are discussed. [Copyright &y& Elsevier]

Abstract: It is important to optimize the resonance ionization efficiency of the sputtered particle by evaluating the internal energy of it. And also the dependence of the change of the internal energy of it on primary ion species and accelerating voltages was investigated. For this study, we developed proto-type resonance laser ionization SNMS instrument, which is a quadrupole SIMS apparatus combined with a wavelength tunable laser. The internal energy of the sputtered aluminum atoms, which has lowly lying excited state (112cm−1) on the ground state, was monitored. As the results, the internal energy of the sputtered aluminum atoms was not influenced by the change of the surface work function and primary ion beam energy at all. On the contrary, the density on lowly lying excited state drastically increased due to the existence of the oxygen on aluminum surface. [Copyright &y& Elsevier]

Abstract: We present ab initio calculation results for electron–phonon (e–ph) contribution to hole lifetime broadening of the surface state on Al(001). We show that e–ph coupling in this state is significantly stronger than in bulk Al at the Fermi level. It makes the e–ph decay channel very important in the formation of the hole decay in the surface state at . We also present the results for e–e lifetime broadening in a quantum-well state in 1ML K/Cu(111). We show that this contribution is not negligible and is much larger than that in a surface state on Ag(111). [Copyright &y& Elsevier]