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We present the first work of the synthesis mechanism from graphene quantum dots (GQDs) to carbon nanotubes (CNTs) by an ion-sputtering assisted chemical vapor deposition. During the annealing process, a Pt thin film deposited by the ion-sputtering was dewetted and agglomerated to form many nanometer-sized particles, leading to Pt nanoparticles (PtNPs) that can act as catalysts for creating carbon allotropes. The shape of the allotropes can be effectively tailored from GQDs to CNTs by controlling three key parameters such as the dose of catalytic ions (D), amounts of carbon source (S), and thermal energy (T). In our work, it was clearly proved that the growth control from GQDs to CNTs has a comparably proportional relationship with D and S, but has a reverse proportional relationship with T. Furthermore, high-purity GQDs without any other by-products and the CNTs with the cap of PtNPs were generated. Their shapes were appropriately controlled, respectively, based on the established synthesis mechanism.
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We have developed a new analytical peak separation analysis for superposed [Formula: see text]-ray peaks on [Formula: see text]Cu and [Formula: see text]Ga to measure the [Formula: see text]Zn(p,2p)[Formula: see text]Cu and [Formula: see text]Zn(p,2n)[Formula: see text]Ga reactions, unlike in most previous works that were employing a radiochemical separation to measure them. Based on the nuclear data such as the [Formula: see text]-ray intensity and the half-life for each nuclide, we may develop a new analytical method that enables us to estimate the respective counts arising from each nuclide, thereby obtaining the nuclear reactions. The newly developed analytical method can universally be applied to separate the superposed [Formula: see text]-ray spectra of any two nuclides, especially superior in separating the nuclides with different half-lives. In comparison with the data in the literature, the two reactions in the present work are in good agreement with those of some previous works. In addition, we compared the present [Formula: see text]Zn(p,2n)[Formula: see text]Ga reaction without the peak separation to the data in the literature without the chemical separation, and find that a good agreement is evident, enhancing the reliability of the [Formula: see text]Zn(p,x)[Formula: see text]Zn and [Formula: see text]Zn(p,3n)[Formula: see text]Ga reactions, which are further measured in the present work.
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Zinc , Reproducibilidad de los ResultadosRESUMEN
We have developed chelator-free copper-64-incorporated iron oxide (IO) nanoparticle (NPs) which have both magnetic and radioactive properties being applied to positron emission tomography (PET)-magnetic resonance imaging (MRI). We have found that the IO nanoparticles composed of radioactive isotope 64Cu may act as a contrast agent being a diagnostic tool for PET as well as a good T2 MRI nanoprobe due to their good r2/r1 ratio. Furthermore, we demonstrate that the 64Cu incorporation at the core of core-shell-structured IO NPs exhibits a good in vivo stability, giving us an insightful strategy for the design of a contrast agent for the PET-MRI system.
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The relaxation behavior in the topological insulator (TI) Bi0.5Sb1.5Te3 has been investigated using 125Te nuclear magnetic resonance spectroscopy. We systematically investigate the spin-lattice relaxation rate (1/T 1) in bulk electronic states with varying particle sizes. By analyzing the 1/T 1 relaxation behavior, we find that with decreasing particle sizes the electronic states in the bulk exhibit more topological insulating behavior, indicative of an increasing energy gap supported by higher thermal activation energy. Besides, the decreasing density of states at the Fermi level was observed in the massive Dirac electrons with decreasing particle size by analyzing the spin-lattice relaxation according to a theoretical model in this spin-orbit coupled system.
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We investigate the magnetic properties in carbonyl iron (CI) particles before and after Ni[Formula: see text] and H[Formula: see text] ion beam irradiation. Upon increasing temperatures, the saturation magnetization ([Formula: see text]) in hysteresis loops exhibits an anomalous increase at a high temperature for the unirradiated and the Ni[Formula: see text]-beam-irradiated samples, unlike in H[Formula: see text]-beam-irradiated sample. Moreover, the magnetization values at low and high temperatures are more intense after Ni[Formula: see text] beam irradiation, whereas after H[Formula: see text] beam irradiation those are remarkably suppressed. Hematite ([Formula: see text]-Fe[Formula: see text]O[Formula: see text]) phase introduced on the surface of our CI particles undergoes the Morin transition that was observed in our magnetization-temperature curves. The Morin transition causing canted antiferromagnetism above the Morin temperature was found in the unirradiated and Ni[Formula: see text]-beam-irradiated samples, but not in H[Formula: see text]-beam-irradiated sample. It is thus revealed that the CI particles undergoing the Morin transition cause the anomalous increase in [Formula: see text]. We may suggest that Ni[Formula: see text] ion beam increases uncompensated surface spins on the CI particles resulting in a more steep Morin transition and the intensified [Formula: see text]. Ion-beam irradiation may thus be a good tool for controlling the magnetic properties of CI particles, tailoring our work for future applications.
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Nitrogen ion implantation is a useful technique to put nitrogen ions into lattices. In this work, nitrogen ion implantation into epitaxial Mo films is performed to create a buried superconducting γ-Mo2N. Atomically flat epitaxial (110) Mo films are grown on (0001) Al2O3. By impinging nitrogen ions, where the beam energy is fixed to 20 keV, we observe (111) γ-Mo2N diffraction and the formation of a γ-Mo2N layer from X-ray reflectivity. Magnetization and transport measurements clearly support a superconducting layer in the implanted film. Our strategy shows that formation of a buried superconducting layer can be achieved through ion implantation and self-annealing.
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The diffusion properties of H(+) in ZnO nanorods are investigated before and after 20 MeV proton beam irradiation by using (1)H nuclear magnetic resonance (NMR) spectroscopy. Herein, we unambiguously observe that the implanted protons occupy thermally unstable site of ZnO, giving rise to a narrow NMR line at 4.1 ppm. The activation barrier of the implanted protons was found to be 0.46 eV by means of the rotating-frame spin-lattice relaxation measurements, apparently being interstitial hydrogens. High-energy beam irradiation also leads to correlated jump diffusion of the surface hydroxyl group of multiple lines at ~1 ppm, implying the presence of structural disorder at the ZnO surface.
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The triplet-triplet annihilation (TTA) efficiency in bicomponent organic systems is investigated by employing a gap plasmon resonator. In our structure, strong absorption peaks arising from coupling between localized surface plasmons and surface plasmon polaritons closely overlap the Q band of porphyrin, leading to higher triplet concentrations within the film. We find that at ultralow excitation intensities on the order of watts per square centimeter (W cm(-2)), TTA becomes predominant for the organic system on a gap plasmon resonator. A strong surface-enhanced Raman scattering intensity is observed in this substrate, verifying the near-field enhancement.
