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Nanowires (NWs) are essential building blocks of photonic devices for guiding light waves. However, the controlled synthesis of non-circular NWs remains challenging. Herein, we develop a bottom-up approach for the fabrication of high-quality elliptical gold NWs with finely tuned geometry engineering by using an advanced ion-track template technology. Compared to ordinary NWs, the rotational symmetry breaking leads to highly polarization-dependent plasmonic responses. Modal analysis shows that the lowest dipolar HE1 mode splits into two branches where the attenuation of the long-range branch decreases by 40%, while the short-range branch has a stronger enhanced near-field. Novel, to the best of our knowledge, plasmonic Fabry–Pérot resonances on finite NWs are measured. Our method can be extended to fabricate non-circular NWs with other materials, holding potential for novel applications from quantum to collective scales.

Extracting clean energy by converting the salinity gradient between river and sea into energy is an effective way to reduce the global pollution and carbon emissions. Reverse electrodialysis (RED) is of great importance to realize the energy conversion assisting the ion-selective membrane. However, its higher ion resistance and lower conversion efficiency results in the undesirable power conversion performance. Here, we demonstrate a 1D/2D hybrid nanochannel system to achieve high osmotic energy conversion and output power. This heterogeneous structure is composed of two structures, in which the subnanometer nanochannels in graphene oxide membrane (GOM) can serve as a selective layer and reduce the ion diffusion energy barrier, while the nanochannel in the polymer can introduce asymmetry to enhance ionic rectification and conversion efficiency. This heterogeneous membrane exhibits excellent cation selectivity and enhanced ionic current rectification (ICR) performance. The application of the GOM/PET hybrid nanochannel system in osmotic energy harvesting is evaluated, and the output power can reach up to 118.2 pW with the energy conversion efficiency of 40.3%. Theoretical calculation indicates that the 1D/2D hybrid system can effectively take the advantage of excellent cation selectivity of 2D lamellar nanochannels to improve its RED performance significantly.

Bioinspired nanoporous membranes show great potential in ionic separation and water filtration by offering high selectivity with less permeation resistance. However, complex processes always limit their applications. Here, we report a convenient approach to introduce ionic selective channels in a micron-thick polycarbonate membrane through swift heavy ion irradiation accompanied by UV sensitization and pulsed-electrical etching. The characteristic dimension of channels was tuned through regulating energy loss of the incident ion and UV sensitization time of the membrane, resulting in the sub-nanoporous membranes with mean channel diameter ranging from2.4 to 9.7 Å. These membranes showed the voltage-activated ionic transport properties associated with the dehydration effect, and the corresponding

Porous membrane-based nanofiltration separation of small biomolecules is a widely used biotechnology for which size-based selectivity is a critical parameter of technological relevance. Efficient determination of size selectivity calls for an advanced detection method capable of performing sensitive, rapid, and on-membrane examination. Surface-enhanced Raman spectroscopy (SERS) is such a detection method that has been widely recognized as an ultrasensitive technique for trace-level detection with sensitivity down to the single-molecule level. In this work, we for the first time develop a double-sided hierarchical porous membrane-like plasmonic metasurface to realize high-selectivity bimolecular separation and simultaneous ultrasensitive SERS detection. This highly flexible device, consisting of subwavelength nanocone pairs surrounded by randomly orientated sub-5 nm nanogrooves, was prepared by combining customized "top-down" fabrication of conical nanopores in an ion-track registered polycarbonate membrane and self-assembly of nanogrooves on the membrane surface through physical vapor deposition. The unique tip-to-tip oriented conical nanopores in the device enables excellent size-based molecular selectivity; the hierarchical groove-pore structure supports a peculiar cascaded electromagnetic near-field enhancement mechanism, endowing the device with SERS-based molecular detection of ultrahigh sensitivity, uniformity, repeatability, and polarization independence. With such dual structural merits and performance enhancement, we demonstrate effective nanofiltration separation of small-sized adenine from big-sized ss-DNA and synergistic SERS determination of their species. We experimentally demonstrate an ultrasensitive detection of 4-mercaptopyridine down to 10 pM. Together with its unparalleled mechanical flexibility, this double-side-responsive plasmonic metasurface membrane can find great potential in real-world molecular filtration and detection under extremely complex working conditions.

Magnetic nanostructures with conical shape are highly desired for pursuing extraordinary magnetic properties and microwave absorption. However, the fabrication of such nanostructures with controlled shape and size uniformities and alignment is not yet realized. Accordingly, the magnetic properties and their application as microwave absorber are not well understood. Here, we report on the first demonstration of controlled fabrication of soft magnetic nickel nanocone arrays with sharp geometry, large aspect ratio, uniform size, and parallel alignment. The imaginary part of the relative complex permeability shows multiband absorption in the 2-17 GHz range. Such an exceptional microwave absorption results from the uniform conical shape and size and the parallel alignment. The absorption mechanisms are discussed under the framework of natural resonance and exchange resonance. The natural resonance is dependent on the shape anisotropy and facilitated by the conical geometry. The exchange resonance is well explained by the observation of the bulk spin waves with exchange coupling at the tip of nanocones using the inelastic light scattering and is consistent with exchange theory predictions for the quantization of bulk spin waves. We expect that our work will shed light on the physical insights into the magnetic properties of nanocones and find great potential in applications of microwave absorption.

Geometry design based plasmon hybridization represents an efficient means for pursuing desired spectral response and near-field enhancement in hybrid structures. Here, we propose to merge individual metal nanostructures into a superstructure to simultaneously realize plasmon mode inheritance and hybridization and electric near-field nanofocusing. As a model demonstration, we combine a metal nanoring supporting two localized surface plasmon resonances (LSPRs) and a metal nanocone sustaining one LSPR and one propagating surface plasmon polaritons (SPPs) mode into a hollow nanocone superstructure, and show numerically that such superstructure exhibits multiple plasmon resonance bands in the visible and near-infrared range and efficient nanofocusing of electric near-fields to the nanocone open apex. We further fabricate the designed superstructure with an ion-track membrane template method that allows for flexible control over relevant structural parameters by varying track etching time. Dark-field scattering measurements on single hollow nanocones confirm the presence of multiple plasmon resonances; surface-enhanced Raman spectroscopy further corroborates that the nanofocusing of electric fields plays a critical role in signal enhancement. We believe that such multi-resonant plasmonic superstructures with efficient near-field nanofocusing capability can find great potential in fundamental nonlinear optics and hot-carrier science studies and practical applications in surface-enhanced spectroscopies and broadband solar light harvesting.

In order to investigate the defects induced by displacement cascade in gold nanotubes, primary knock-on atoms with kinetic energies of 1 keV were introduced at the exterior surface of the nanotubes. The evolution of the collision cascade as well as the defects generated in the nanotube were studied using molecular dynamics simulation. We found that point defects and stacking faults were induced by the cascade. The interior surface of the nanotube acts as the sinks to absorb the point defects as the same as the exterior surface does, especially when the distance between them is decreased. Consequently, both the two surfaces influence the time evolution and the residual number of point defects in the nanotubes. In the gold nanotubes with fixed external diameter, the number of interstitials is decreased with the internal diameter increasing, while the number of vacancies does not show a clear trend with the variation of the internal diameters. The probability of formation of stacking faults is higher in gold nanotubes with larger internal diameters which caused by the fact that the formation of stacking faults is facilitated by the interior surface. The results show that, due to the specific geometry of the nanotubes, the evolution and the production of the cascade-induced damage has its own features.

Changes in electrical properties of graphene devices induced by the energetic ion irradiation are very important for their application in harsh radiation environment. This paper presents the modulating behavior of electrical properties of graphene-based devices induced by swift heavy ions (SHIs). Graphene field effect transistors (GFETs) were irradiated by 1.79 GeV Ta ions and it was found that at lower fluence (109-1010 ions/cm2), the SHIs irradiation can effectively optimize the performance of GFETs, while at higher fluence (∼1011 ions/cm2), the electrical properties of the devices were significantly deteriorated after the irradiation process. The effective length and width of the graphene strip and irradiation fluence are the main factors that determine the improvement in performance of GFETs. Raman spectroscopy was employed to figure out the correlation between the initial defect density in graphene and changes in electrical performance of GFETs. It was shown that the competition among various factors such as the doping, local annealing and defect creation dominates the GFET performance. This work explores the best conditions for improving the electrical properties of GFETs and provides an important reference data for the utilization of graphene based irradiated devices in aerospace electronics.

High-performance X-ray detectors have immense potential in medical and security inspections. However, the current X-ray detectors are limited in flexible, high-spatial-resolution large-scale detection, and integration for imaging. Here, nuclear track-etched porous polyethylene terephthalate (PET) is developed as the template for preparing uniform, large-area (≥10

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne experiment, in operation since 2015, aimed at studying high-energy gamma rays and cosmic nuclei fluxes. Of the various sub-detectors in the DAMPE payload, the Silicon-Tungsten tracKer-converter (STK) plays a significant role in the charge measurement of incoming ions. Depending on the angle of inclination of the impinging particle and its position of impact on these strips, the collected charge can spread between the strips which results in some fractional signal loss. The $\eta$ variable is used to identify this spread of charge across the strips and correct for the associated charge loss. This brings us closer to accurate determination of particle charge which is crucial for ensuring a good discrimination between particles. The $\eta$-correction is, therefore, expected to play an important role in the determination of heavy ions by the DAMPE detector. It has helped reduce the proton background for the helium identification in STK by a factor of 1.5 for MIP tracks. It has been sucessfully applied to carbon nuclei and its application to heavier nuclei is currently being studied.

Since its launch, in December 2015, the satellite-based DAMPE (DArk Matter Particle Explorer) particle detector is taking data smoothly. The Silicon-Tungsten tracKer-converter (STK) of DAMPE consists of six tracking planes (6x, 6y) of single-sided silicon micro-strip detectors mounted on seven support trays. The STK is able to measure the charge and precisely reconstruct the track of traversing charged particles. Tungsten plates (1 mm thick) are integrated in the second, third and fourth tray from the top to serve as $\gamma \rightarrow e^+e^−$ converters. Commissioned rapidly after the launch, the STK is running extremely well since then. The STK in-orbit calibration and performance during its first more than 5 years of operation, including the noise behaviour and the thermal and mechanical stability, are presented in this contribution.

The DArk Matter Particle Explorer (DAMPE) is the first Chinese cosmic-ray direct detection experiment. It has been operating smoothly on-orbit since its successful launch at the end of 2015. Currently, its sub-detectors and the satellite are in good working order. The DAMPE payload employs a BGO Calorimeter for energy measurements, trigger and e/p identification. The calorimeter is constructed of 308 BGO crystals, and PMTs are coupled to the crystals with optical filters to readout scintillation light. In this work, we present the status and performance of the calorimeter, including status of detector units, energy measurement, especially in TeV range, detector endurance, and long term performance in a duration of 65 months.

The Fermi bubbles are two large structures above and below the Galactic Plane. They are first discovered by Fermi-LAT and thought to be related to the jet or the wind from the Galactic center. The DArk Matter Particle Explorer (DAMPE) is a space-borne high energy particle telescope aiming at measuring cosmic rays and photons in a broad energy range. In this work, we use 4.8 years of DAMPE photon data to search for the emission from the Fermi Bubbles. We calculate the TS values of the lobes and the significance of its curved spectrum. The obtained spectral parameters are then compared with those from the Fermi-LAT. We also search for the emission from the cocoon in the southeast part of lobes. Since the Galactic diffuse emission (GDE) model is a major source of systematic uncertainty, we also switch to the GDE models calculated with Galprop and evaluate the influence.

The DArk Matter Particle Explorer (DAMPE), a space-based high energy particle detector, has been operated on-orbit for more than five years. The large geometric factor and good charge resolution enable DAMPE to have very good potential to measure cosmic-rays up to 100 TeV. Knowledge of the boron to carbon (B/C) flux ratio is very important in understanding the prop- agation of cosmic rays, especially in TeV energy range. In this contribution, the latest progress of the B/C flux ratio analysis based on the flight data collected by DAMPE during the 5 years of operation, is presented.

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the DArk Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of $4.3\sigma$. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out., Comment: 11 pages, 13 figures, published in Phys. Rev. Lett. Add one more digit for first three columns in Table S2

Graphene oxide (GO) has become a promising 2D material in many areas, such as gas separation, seawater desalination, antibacterial materials, and so on because of its abundant oxygen-containing functional groups and excellent dispersibility in various solvents. The graphene oxide membrane (GOM), a laminar and channel-rich structure assembled by stacked GO nanosheets, served as a kind of precise and ultrafast separation material has attracted widespread attention in membrane separation field. To break the trade-off between ion permeability and ion selectivity of separation membrane based on GOM, GOM/conical nanopore system is obtained by spin-coating ultrathin GOM on PET conical nanopore, which possesses ion rectification property. Comparing to pure PET conical nanopore, the existence of GOM not only enhances the cation conductance but also makes the ion rectification ratio increase from 4.6 to 238.0 in KCl solution. Assisted by COMSOL simulation, it is proved that the GOM can absorb large amount of cations and act as cation source to improve the ion selectivity and rectification effect of GOM/conical nanopore system. Finally, the chemical stability of GOM/conical nanopore is also investigated and the corresponding results reveal that the GOM/conical nanopore system can perform the ion rectification behavior in a wider pH range than pure PET conical nanopore. The presented findings demonstrate the great potential applications of GOM/conical nanopore system in ionic logic circuits and sensor systems.

Surface-enhanced Raman scattering (SERS), due to its high detecting sensitivity and rapid data acquisition ability, has been considered as a powerful technique for label-free ultrasensitive detection of chemical and biochemical analytes. As an important part, the uniform SERS substrate is the prerequisite for this technology being used in all the related areas. Therefore, seeking the fast, convenient and low-cost way to obtain the SERS substrate with high performance and reproducibility never stops in recent decades. In this work, the PC membrane with uniform nanopores obtained by ion irradiation and chemical etching (i.e., ion-track etched PC membrane) was first used to prepare the gold nanostar SERS substrate. The monolayer gold nanostars can be obtained through a one-step redox reaction on the surface of the PC membrane, which not only can act as the base of SERS substrate but also can work as the reaction adjuster. By optimizing the growth conditions, the SERS substrate with uniform monolayer gold nanostars can be fabricated without any complicated procedures and costly equipment fast (in 20 mins). Meanwhile, the prepared flexible gold nanostar SERS substrate exhibits excellent Raman performance, which can effectively detect the analyte R6G with the concentration as low as 1 × 10

Nuclear track membrane is a new type of membrane material with uniform pore size distribution. It can be used as a high-precision filtration membrane and there is a wide range of applications in sewage treatment, cell filtration, and biomedicine. The main production processes of nuclear track membrane include heavy ion irradiation and chemical etching, so there is a great significance about the research and design of etching lines. The main contents studied in this paper include the physical design principle of the etched line, the basic engineering structure, the basic control system architecture, and a complete HMI. The research plays an important role in the development and large-scale application of nuclear track membrane in this paper.

A typographical error remains in the publication of the first name of Aymann S. El-Said: Aymann should be written as Ayman.

International audience; Sputtering experiments were performed by irradiating LiF, NaCl, and RbCl crystals with various swift heavy ions like S, Ni, I, Au with energies between 60 and 210 MeV, C$_{60}$ clusters between 12 and 30 MeV or Pb ions between 730 and 6040 MeV. Sputtered species are collected on arc-shaped catchers and subsequently analyzed by elastic recoil detection analysis or Rutherford backscattering analysis. The study focuses on angular distributions and total yields for LiF and covers a broad range of experimental parameters including cleaved or rough sample surfaces, ion fluence, beam incident angles, and different ion velocities leading to electronic energy loss (S$_{e}$) values from 5 to 45 keV/nm. In most cases, the angular distribution has two components, a jet-like peak perpendicular to the surface sample superimposed on a broad isotropic cosine distribution whatever is the beam incident angle. The observation of the jet depends mainly on the surface flatness and angle of ion incidence. However, the jet does not appear clearly when irradiated with C$_{60}$ cluster. The sputtering yield is stoichiometric and characterized by huge total yields of up to a few 10$^{5}$ atoms per incident ion. The yield follows a power law as function of electronic energy loss, Y follows an exponential law with S$_{e}^{n}$ with n ~ 4. While the azimuthal symmetry for sputtering is observed at low ion velocity (~1 MeV/u), it seems to be lost at high velocity (>4 MeV/u). The data provide a comprehensive overview how the angular distribution and the total sputtering yield scale with the energy loss, beam incidence angle and ion velocity. Complementary experiments have been done with NaCl and RbCl targets confirming the observation made for LiF.[graphic not available: see fulltext][graphic not available: see fulltext]

AlGaN/GaN high electron mobility transistor (HEMT) devices were irradiated with swift heavy ions at different fluences. From structural and electrical studies, it was found that SHI irradiation leads to a significant deterioration of structural and electrical properties of the devices. Positive threshold voltage Vth was found to increase by about 85% as a result of irradiation with 1540-MeV 209Bi ions at fluence of 1.7 × 1011 ions/cm2, while this threshold voltage value was increased by 55% after irradiation with 2300-MeV 129Xe at a fluence of 4 × 1011 ions/cm2. The maximum saturation drain current Ids was decreased by about two orders of magnitude in the device after irradiation with 209Bi ions. Quasi-continuous tracks were observed visually in the devices after irradiation with 209Bi ions. The observed defects and disorders induced in the devices by SHI irradiation were found responsible for the decrease in carrier mobility and sheet carrier density, and finally, these defects resulted in the degradation of electrical characteristics of HEMTs.

Dynamic evolutions of morphology and size of swift heavy ion (SHI) induced latent tracks in muscovite mica were explored using in situ transmission electron microscopy (TEM) in this paper. Prior to the measurements, muscovite mica sheets were irradiated with Kr and Bi ions with electronic energy loss (dE/dx)e of 5.9 keV/nm and 31.5 keV/nm, respectively. It is observed in TEM micrographs that the latent tracks in mica are continuously along the cross section view of the ion tracks. The track profile is not found dramatically uniform but rather it is found slightly fluctuating for similar (dE/dx)e values. In situ TEM observation clarify that atoms in the track halo are unstable compared with the lattice atoms in the vicinity of the track. Point defects induced by the electron bombardment are generated preferentially around the track core, which results in the increased diameter of the track.

The sub-nanochannel materials have attracted extensive attention because of the great potentials in ion separation and water filtration due to their unique ionic transport properties. However, effectively preparing the sub-nanoporous membranes with tunable channel size is still a challenge. In this study, a green and convenient method is introduced to prepare sub-nanoporous polyethersulfone (PES) membrane with highly aligned channels by swift heavy ion irradiation, UV sensitization, and water rinse. Through adjusting the membrane's UV sensitization time, the channel diameter of sub-nanoporous PES membrane can be facilely regulated at sub-nanoscale, which is essential to design the tailor-made membranes for specific applications. It is found that ionic transport in sub-nanoporous PES membrane exhibits voltage-activated features associated with the ionic dehydration at angstrom-confined space, with the corresponding I−V characteristics showing a dependence on ion species, channel size, and solution pH. Such a membrane can work as an excellent ion-exchange membrane in electrodialysis ion separation, exhibiting a separation ratio of K+:Na+:Li+:Mg2+ as high as 83:56:14:1 and K+ transport rate up to 0.82 mol h−1 m−2 under 10 V driving force. It is proved that the sub-nanoporous PES membrane also possesses strong chemical and electrochemical tolerances, which are the prerequisites for future utilizations.

Integrating nanowires with nonuniform diameter and random spatial distribution into an array can afford unconventional and additional means for modulating optical response. However, experimental realization of such a nanowire array is quite challenging. In this work, we propose a new fabrication strategy which takes advantage of ion track technology, via sequential swift heavy ion irradiation and ion track etching. Based on this strategy, we unprecedentedly realize nanowire arrays, using gold as an example, with gradient and programmable diameters in a controlled manner. We further demonstrate that such nanowire arrays can support broadband, tunable, and enhanced plasmonic responses. We believe that our new type of nanowire arrays will find great potential in applications such as light management and optoelectronic devices.

Displacement cascade in gold nanowires was studied using molecular dynamics computer simulations. Primary knock-on atoms (PKAs) with different kinetic energies were initiated either at the surface or at the center of the nanowires. We found three kinds of defects that were induced by the cascade, including point defects, stacking faults and crater at the surface. The starting points of PKAs influence the number of residual point defects, and this consequently affect the boundary of anti-radiation window which was proposed by calculation of diffusion of point defects to the free surface of nanowires. Formation of stacking faults that expanded the whole cross-section of gold nanowires was observed when the PKA’s kinetic energy was higher than 5 keV. Increasing the PKA’s kinetic energy up to more than 10 keV may lead to the formation of crater at the surface of nanowires due to microexplosion of hot atoms. At this energy, PKAs started from the center of nanowires can also result in the creation of crater because length of cascade region is comparable to diameter of nanowires. Both the two factors, namely initial positions of PKAs as well as the craters induced by higher energy irradiation, would influence the ability of radiation resistance of metal nanowires.

Cu/Ni multilayer nanowire arrays with well controlled diameters, Cu and Ni layer thickness and varying periodicity were fabricated by multi potential deposition technique in etched ion-track template at room temperature. A facile method was adopted to confirm the different layer thickness and corresponding component by only removing the Cu layer. The pure Ni and Cu layer were confirmed in the Cu/Ni multilayer nanowires by using the new method and XRD analysis. The relationships between the coercivity and nanowire diameter, layer thickness and periodicity were obtained by carrying out vibrating sample magnetometry (VSM) measurement. The results indicated that the coercivity of multilayer nanowire arrays can be tuned significantly by nanowire diameter, periodicity, Cu and Ni layer thickness. In order to explain the experimental phenomena, Pant's model was modified and adopted to successfully explain the variation of demagnetizing field in Cu/Ni multilayer nanowire arrays after tailoring multiple parameters. Keywords: Multilayer nanowires, Coercivity, Electrochemical deposition, Demagnetizing field

Nanoplates of nickel-substituted manganese ferrite (M 0.8 Ni 0.2 Fe 2 O 4 ) with side-length of 8 ± 2 nm were fabricated by coprecipitation route. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and Raman spectroscopy, which confirmed the formation of single phase crystalline nanoparticles with plate–like morphologies. Magnetic properties were investigated by vibrating sample magnetometer at room temperature and by zero-field cooled (ZFC) and field cooled (FC) M(T) measurements in the temperature range 20–300 K, which revealed the superparamagnetic nature of the samples with blocking temperature of about 90 K. Benefited from the plate-like morphology of the samples, the electrochemical performance was tested in lithium ion batteries, which shows the initial discharge and charge capacities of ∼1050 mAhg −1 and ∼900 mAhg −1 for the first cycle and excellent coulombic efficiency of higher than 95% after the ten subsequent cycles. This work demonstrates the possibility of using plate–like M 0.8 Ni 0.2 Fe 2 O 4 nanoparticles as the anode materials for lithium-ion batteries.

For understanding the interaction between light and noble/magnetism multilayer nanowires, Cu/Ni multilayer nanowires are fabricated by a multi-potential step deposition technique in etched ion-track polycarbonate template. The component and the corresponding layer thickness of multilayer nanowire are confirmed by TEM and EDS line-scan analysis. By tailoring the nanowire diameter, the Cu layer thickness and the periodicity of the nanowire, the extinction spectral of nanowire arrays exhibit an extra sensitivity to the change of structural parameters. The resonance wavelength caused by surface plasmon resonance increases obviously with increasing the nanowire diameter, the Cu layer thickness and the periodicity. The observations in our work can be explained by the “impurity effect” and coupled effect and can also be optimized for developing optical devices based on multilayer nanowires.

Nickel substituted manganese ferrite [NixMn1−xFe2O4 (x = 0.2)] nanoplates with cubic shape and controlled sizes were fabricated by chemical coprecipitation technique. Structural analyses confirmed the formation of single phase crystalline nanoplates in the size range 8–24 nm. Magnetic studies showed that coercivity as a function of plate length goes through a maximum, peaking at 162 Oe and then decreases for larger nanoplates, indicating that the single domain limit for NixMn1−xFe2O4 (x = 0.2) is ∼21 nm. While negligible coercivity at below 10 nm confirms the superparamagnetic limit in the range 8–10 nm for these nanoplates. Saturation magnetization of the samples was found to increase linearly with plate length in the single domain regime, however this increase was observed slower for the larger nanoplates. Typical blocking effects were studied in the temperature range 20–300 K and it was found the superparamagnetic blocking temperature increases monotonically with increasing size of the nanoplates. The results are discussed in terms of the enhanced surface roles and variation of surface and effective anisotropies with size of the nanoplates that strongly influence their magnetic properties within the domain of Stoner Wohlfarth model for ferromagnetic systems.

We demonstrate fabrication and magnetic characterization of novel nanostructures composed of Ni nanowires decorated with Co nanoparticles by two step etching and electrochemical deposition in polycarbonate template. Structural analysis confirmed the formation of nickel nanowires with diameter of 62 nm which are surrounded by cobalt nanoparticles of about 15 nm in diameter. By electron microscopy analyses it is evident that the nanoparticles are distributed on the surface of the nanowires. Analysis of magnetization data indicates that ferromagnetic Ni nanowires exhibit an easy axis of magnetization parallel to the wire long-axis while the angular dependence of coercivity indicates that magnetization reversal occurs through the curling process in these nanowires. An exchange bias accompanied by vertical shift in magnetization was observed below ∼20 K, measured under a cooling field of 1 kOe, which is attributed to the spin interactions between the spin-glass like surface layer and ferromagnetic core of the nanowires and nanoparticles.

DAMPE satellite has directly measured the cosmic ray proton spectrum from 40 GeV to 100 TeV and revealed a new feature at about 13.6 TeV., The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

We develop a metric-torsion theory for chiral structures by using a generalized framework of transformation optics. We show that the chirality is uniquely determined by a metric with the local rotational degree of freedom. In analogy to the dislocation continuum, the chirality can be alternatively interpreted as the torsion tensor of a Riemann-Cartan space, which is mimicked by the anholonomy of the orthonormal basis. As a demonstration, we reveal the equivalence of typical three-dimensional chiral metamaterials in the continuum limit. Our theory provides an analytical recipe to design optical chirality.

The DArk Matter Particle Explorer (DAMPE), a satellite-based cosmic ray and gamma-ray detector, was launched on December 17, 2015, and began its on-orbit operation on December 24, 2015. In this work we document the on-orbit calibration procedures used by DAMPE and report the calibration results of the Plastic Scintillator strip Detector (PSD), the Silicon-Tungsten tracKer-converter (STK), the BGO imaging calorimeter (BGO), and the Neutron Detector (NUD). The results are obtained using Galactic cosmic rays, bright known GeV gamma-ray sources, and charge injection into the front-end electronics of each sub-detector. The determination of the boundary of the South Atlantic Anomaly (SAA), the measurement of the live time, and the alignments of the detectors are also introduced. The calibration results demonstrate the stability of the detectors in almost two years of the on-orbit operation.

Molybdenum disulphide (MoS2) crystal samples were irradiated by swift heavy ions (209Bi and 56Fe). Hillock-like latent tracks were observed on the surface of irradiated MoS2 by atomic force microscopy. The modifications of properties of irradiated MoS2 were investigated by resonant Raman spectroscopy and ultraviolet–visible spectroscopy (UV–Vis). A new peak ( E 1 u 2 , ∼385.7 cm−1) occurs near the in-plane E 2 g 1 peak (∼383.7 cm−1) after irradiation. The two peaks shift towards lower frequency and broaden due to structural defects and stress with increasing fluence. When irradiated with high fluence, two other new peaks appear at ∼ 190 and ∼ 230 cm−1. The peak at ∼230 cm−1 is disorder-induced LA(M) mode. The presence of this mode indicates defects induced by irradiation. The feature at ∼460 cm−1 is composed of 2LA(M) (∼458 cm−1) and A 2 u (∼466 cm−1) mode. With increasing fluence, the integrated intensity ratio between 2LA(M) and A 2 u increases. The relative enhancement of 2LA(M) mode is in agreement with the appearance of LA(M) mode, which both demonstrate structural disorder in irradiated MoS2. The ∼423-cm−1 peak shifts toward lower frequency due to the decrease in exciton energy of MoS2, and this was demonstrated by the results of UV–Vis spectra. The decrease in exciton energy could be due to introduction of defect levels into band gap.

Highly oriented pyrolytic graphite (HOPG) was irradiated with 40.5 MeV 112Sn ions at a range of fluence: 1 × 1012–1 × 1014 ions/cm2. A new Raman band was observed at ∼864 cm−1 which grows with increasing the irradiation fluence. This band has been observed in Raman spectra of HOPG and natural graphite crystal edge planes, only when the incident light is polarized perpendicular to the basal planes and it has been assigned to the out-of-plane Raman-inactive B2g mode which becomes Raman active due to a slight rearrangement of lattice structure at the edge. However, we first obtained this band in Raman spectra of basal planes of irradiated HOPG with the polarization of the incident light parallel to the basal planes. Then, a half-wave plate was used to change the polarization direction of the incident light in the HOPG basal planes. The intensity of the band at 864 cm−1 is almost independent of the incident light polarization direction. We suggest that re-crystallized graphite with random lattice orientations are formed during ion irradiation, which gives rise to the B2g band. The conclusion is confirmed by transmission electron microscopy images, showing that there are some randomly orientated nanoscale graphite crystals surrounded by amorphous carbon.

InP crystals and GaN films were irradiated by swift heavy ions 86 Kr and 209 Bi with kinetic energies of 25 and 9.5 MeV per nucleon and ion fluence in the range 5 × 10 10 to 3.6 × 10 12 ions/cm 2 . The characteristic optical bands were studied by Raman spectroscopy to reveal the disorder and defects induced in the samples during the irradiation process. The crystallinity of InP and GaN was found to be deteriorated after irradiation by the swift heavy ions and resulted in the amorphous nature of the samples along the ion tracks. The amorphous tracks observed by transmission electron microscopy (TEM) images confirmed the formation of lattice defects. In typical F 2 (LO) mode, in case of InP, the spectra shifted towards the lower wavenumbers with a maximum shift of 7.6 cm −1 induced by 1030 MeV Bi ion irradiation. While in case of GaN, the typical E 2 (high) mode shifted towards the higher wavenumbers, with maximum shift of 5.4 cm −1 induced by 760 MeV Bi ion irradiation at ion fluence of 1 × 10 12 ions/cm 2 . The observed Raman shifts reveal the presence of lattice defects and disorder induced in the samples after irradiation by the swift heavy ions. This irradiation also generated lattice stress in the samples, which has been investigated and discussed in detail in this work.

Highly oriented pyrolytic graphite (HOPG) and monolayer graphene were irradiated by swift heavy ions (SHI, 479 MeV 86 Kr and 250 MeV 112 Sn) and highly charged ions (HCI, 4 MeV 86 Kr 19+ ). The irradiation effects caused by different types of irradiation were investigated by Raman spectroscopy. It was found that the intensity ratio of D peak to G peak ( I D /I G ) in the case of HCI was higher than that of SHI for the same ion fluence in HOPG. The larger I D /I G indicates that synergistic effects of kinetic and potential energies of medium energy HCI has to be considered during the energy deposition process. A turning point was detected during the evolution process of I D / I G with fluence obtained from SHI and HCI impacted graphene, while such turning point was absent in the case of HOPG. The Lucchese's phenomenological model was modified and the experimental data of I D / I G vs. fluence for HOPG and graphene was completely following the modified model. According to this model, energetic ions induced both structurally disordered and activated regions in graphene. The competing mechanism of these two regions resulted in three different trends of the I D /I G variation in the case of graphene whereas in HOPG, such mechanism was not observed.

Core-shell magnetic nanowires of nickel and cobalt embedded in ion-track etched polycarbonate (PC) template were fabricated by two step etching and deposition technique. Structural investigations reveal the successful fabrication of 60 nm nickel core nanowires surrounded by ∼20 nm concentric cobalt shell. X-ray diffraction and electron microscopy studies confirmed the presence of fcc nickel and hcp cobalt at the core and shell regions, respectively. Low temperature magnetic studies performed between 5 and 300 K indicate the ferromagnetic nature of the nanowires with coercivity and magnetization that are increasing with decreasing temperature of the nanowires. Temperature dependence of coercivity can be understood in term of thermal activation over the energy barrier with m -power dependence on the field, while the saturation magnetization was found to follow the modified Bloch's law at low temperatures.

Chemical stability of metal nanowires is a great concern for many practical applications. Metal nanowires deposited in the pores of various templates have been considered oxidization-resistant because the templates provide natural protection. Here we present the first ever attempt to investigate the oxidation behavior of copper nanowires supported in a template matrix using a surface-plasmon-based optical spectroscopy method combined with high-resolution transmission electron microscopy (TEM). Although the nanowires are protected by being embedded in the polymer template matrix, unexpected oxidation is clearly observed in TEM imaging, which unambiguously reveals the possible underlying oxidation mechanism responsible for the oxidation passivation. By measuring the optical properties with localized surface plasmon resonance spectroscopy, the oxidation behavior of the copper nanowires is studied as a function of storage time in both air and vacuum and thus uncovers the oxidation dynamics of copper. Finally, we demonstrate that the oxidation can be entirely prevented by sealing the open ends of the wires, which is confirmed by monitoring the electrical resistance of single nanowires. Our results have significant importance in understanding the oxidation behavior of metal nanostructures in general and also provide useful guidelines to estimate their electrical functionality in optoelectronic devices.

Metal nanostructures with conical shape, vertical alignment, large ratio of cone height and curvature radius at the apex, controlled cone angle, and single-crystal structure are ideal candidates for enhancing field electron-emission efficiency with additional merits, such as good mechanical and thermal stability. However, fabrication of such nanostructures possessing all these features is challenging. Here, we report on the controlled fabrication of large scale, vertically aligned, and mechanically self-supported single-crystal Cu nanocones with controlled cone angle and enhanced field emission. The Cu nanocones were fabricated by ion-track templates in combination with electrochemical deposition. Their cone angle is controlled in the range from 0.3° to 6.2° by asymmetrically selective etching of the ion tracks and the minimum tip curvature diameter reaches down to 6 nm. The field emission measurements show that the turn-on electric field of the Cu nanocone field emitters can be as low as 1.9 V/μm at current density of 10 μA/cm(2) (a record low value for Cu nanostructures, to the best of our knowledge). The maximum field enhancement factor we measured was as large as 6068, indicating that the Cu nanocones are promising candidates for field emission applications.

Nanocrystalline ferrites with general formula of Co1−xMnxFe2O4 (0 ⩽ x ⩽ 1) have been synthesized via wet chemical coprecipitation technique. Structural and magnetic investigations were performed at room temperature. The results revealed the formation of single phase Mn-substituted CoFe2O4 nanoparticles with crystallite sizes in the range 12–15 nm. An increase in lattice parameter and decrease in X-ray density were observed with increasing Mn concentration in CoFe2O4. FTIR results showed two (vibrational) frequency bands (υ1 and υ2) for tetrahedral and octahedral sites confirming the formation of spinel ferrite. Magnetic measurements showed increasing behavior of both coercivity and saturation magnetization of cobalt ferrite up to 20–30% manganese concentration followed by a monotonic decrease in these parameters for higher Mn concentrations.

Cu-Ni core-shell nanowires, with an inner Cu core diameter of about 60 nm and varying Ni shell thicknesses (10, 30, 50, 60, and 80 nm), were successfully fabricated in porous polycarbonate (PC) iontrack templates by a two-step etching and electrodeposition method. In our experiment, the thickness of Ni shell can be effectively tuned through the etching time of templates. The core-shell structure was confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The X-ray diffraction (XRD) pattern elucidates the co-existence of characteristic peaks for both Cu and Ni, indicating no other phases were formed during preparation. Magnetic hysteresis loops measured via vibrating sample magnetometry (VSM) revealed that Cu-Ni core-shell nanowires with thinner Ni shell exhibited obviously diamagnetic character and together with a weak ferromagnetic activity, whereas ferromagnetic behavior was primarily measured for the wires with thicker Ni shell. With increasing Ni shell thickness, the squareness and coercivity value became smaller due to the shape anisotropy and the formation of multi-domain structure.

The environmentally friendly preparation of nanomaterials with controlled structural features represents a development trend of nanoscience and nanotechnology. In this work, using a cyanide-free bath, gold nanowires with controlled crystallinity and preferred crystallographic orientation have been prepared by electrochemical deposition in home-made polycarbonate ion track-etched templates. Single-crystal and polycrystal gold nanowires with preferred orientations along the [111] and [100] directions have been obtained by selecting fabrication parameters. The influence mechanisms of nanopore diameter, applied voltage, and deposition temperature on structural properties are proposed. In addition, single-crystal nanowires with [100] preferred orientation show enhanced field emission, which may be attributed to their single-crystal structure and the lower work function of loosely packed crystal planes.