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In order to clearly understand the physical images of incident ions passing through the insulating nanocapillary, in this work we establish a theoretical model, in which the matlab program is combined with the Monte Carlo method, to estimate the time evolution of transmission features, such as the angular and deposited charge distribution, three-dimensional (3D) trajectories of H+ particles with proton incident energies of 10 keV, 100 keV and 1 MeV at -1 title angle. The simulation results show that the transmission mechanism of 100 keV protons is different from those of 10 keV and 1 MeV protons. After a sufficiently charging and discharging stage, 10 keV H+ particles are guided along the direction of capillary axis, indicating that the guiding force from the surface charge patches is significant, and the small-angle scattering of 1 MeV protons under the capillary inner wall is a physical process that determines the transport of H+ particles through the nanocapillary. However, for 100 keV H+ particles, the centroid angle gradually shifts from the guiding direction to the direction close to the incident beam, which is attributed to the fact that the stochastic inelastic binary collision below the surface is the main transmission mechanism at the beginning. After the charging and discharging reach an equilibrium state, the H+ particles are likely to pass through the nanocapillary, and the main transmission mechanism is the charge-patch-assisted specular scattering. This mechanism deepens the understanding of the transport behavior of protons through the nanocapillary, which will contribute to the control and application of the 100 keV proton beam.

The transmissions of oxygen ions through Al2O3 nanocapillaries each 50 nm in diameter and 10 μm in length at a series of different tilt angles are measured, where the ions with energies ranging from 10 to 60 keV and charge states from 1 up to 6 are involved. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of a guiding effect when ions pass through the capillary and a significant dependence of the ion transmission on the energy and the charge state of the ions. The guiding effects are observed to be enhanced at lower projectile energies and higher charge states. Meanwhile, the results also exhibit that the transmission yields increase as the tilt angle decreases at a given energy and charge state.

This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radiation Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2A±0.25A (1A=0.1 nm) which is coincident with other ones' results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed.

The L-shell x-ray yields of Zr and Mo bombarded by slow Ar16+ions are measured. The energy of the Ar16+ions ranges from about 150 keV to 350 keV. The L-shell x-ray production cross sections of Zr and Mo are extracted from these yields data. The explanation of these experimental results is in the framework of the adiabatic direct-ionization and the binding energy modified BEA approximation. We consider, in the slow asymmetric collisions such as Ar and Mo/Zr, the transient united atoms (UA) are formed during the ion-surface interaction and the direct-ionization is the main mechanism for the inner-shell vacancy production. Generally, the theoretical results are in good agreement with the experimental data.

The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i.e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the twodimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm0.5 mm and a divergence of less than 0.35. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys. Sin. 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i.e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.

Graphene was first discovered in 2004 (Novoselov K S, et al. 2004 Science 306 666), it is a single atomic layer of sp2-bonded carbon atoms arranged in a honeycomb-like lattice. According to its extraordinary electronic, mechanical, thermal and optical properties, one can expect it to have a variety of applications in nanoscale electronics, composite materials, energy storage, and biomedicine fields. Although many experimental and theoretical studies on graphene have been carried, there still exist many obstacles to its applications. A representative example is nanoscale electronics (e.g., field-effect transistors and optoelectronic devices) that requires non-zero band-gap. Therefore, introducing defects into graphene and leading to band-gap opening are key steps for its technique applications.Recently, ion beam irradiation as a defects introducing technique was performed by Lee et al. (2015 Appl. Surf. Sci. 344 52) and Zeng et al. (2016 Carbon 100 16) through 5, 10, and 15 MeV protons and highly charged ions (HCIs) irradiating the graphene separately. Considering the advantages of simplity for preparing samples and feasibility in atmospheric condition of Raman spectroscopy compared with common characterization techniques (high resolution transmission electron microscopy, scanning electron microscopy, atomic force microscopy) for nano-materials, in both studies, Raman spectroscopy is used to obtain the evolution of ID/IG (ID is the peak intensity excited by defects, IG is the peak intensity origining from lateral vibration of carbon atoms) with different energies and fluences, respectively. In this work, considered are the following points:1) the absence of quantitive characterization for defects in the above two studies; 2) the low displacement energy of 25 eV required for a carbon atom to be knocked out (Zhao S J, et al. 2012 Nanotechnology 23 285703); 3) the complex interaction between HCIs and material. The irradiation effects of single layer graphene on silicon substrate are investigated by 750 keV and 1 MeV proton bombarding. This introduces the defects into graphene and thus leads to band-gap opening. By comparing Raman spectra of the samples before and after irradiation, a quantitive characterization about defects in graphene is achieved. Detailed analysis shows that 1) the value of ID/IG increases with the energy loss of incident proton, which is consistent with the result of SRIM simulation; 2) the average distance of defects LD increases with the incident proton energy; 3) the defect density nD decreases with the incident proton energy. These indicate that the damage effect for MeV protons in single layer graphene with substrate is similar to those in three-dimensional materials. The method presented here may facilitate the understanding of the physical mechanism of MeV proton interaction with two-dimensional materials, and provide a potential way of controlling the electronic structure and band-gap.

We investigate angular distributions of the transmitted 60 keV and 120 keV O3+ ions through nanocapillaries with 50nm diameter and 10μm length. The experimental results are in agreement with the 'guiding effect' found by Stolterfoht et al. For different tilted angles of the nanocapillary membrane with respect to the beam, the angular distributions of the transmitted ions are measured by a one-dimensional micro-channel plate (MCP) detector. Moreover, the dependence of this guiding effect on the projectile energy is studied.

The Cu films are deposited on two kinds of p-type Si (111) substrates by ionized cluster beam (ICB) technique. The interface reaction and atomic diffusion of Cu/Si (111) and Cu/SiO2/Si (111) systems are studied at different annealing temperatures by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results are obtained: For the Cu/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230?C. The diffusion coefficients of the samples annealed at 230?C and 500?C are 8.5 ? 10-15 cm2?s-1 and 3.0 ? 10-14 cm2?s-1, respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450?C. The diffusion coefficients of Cu in Si are calculated to be 6.0 ? 10-16 cm2?s-1 at 450?C, due to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si.

The cross section ratios of the double, triple and quadruplicate ionization to the single ionization of argon by 1.5-7.5 MeV partially stripped carbon ions are measured by using time-of-flight technique. The Auger transition and the charge exchange process in the multiple ionization of argon are studied. The ratios of cross sections of the direct multiple ionization to those of the direct single ionization are obtained by subtracting the parts of the Auger transition and the charge exchange process from the measured data. It is found that the cross section ratios of the direct multiple ionization to those of the direct single ionization are in good agreement with the predicted multi-step (ν/qeff)-2n+2 law.

We study the L x-ray emission from Zr, Mo and In targets and M x-ray emission from Pb target under bombardment of low energy Arq+ (q = 13,14,15,16) ions. The relative x-ray yields were measured in the projectile kinetic energy range 210–360 keV. It is found that the relative x-ray yields from Zr, Mo and Pb targets increase with the increasing projectile kinetic energy for Ar14+ and Ar16+ projectiles and depend on the potential energy of the projectile remarkably.

It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.

In recent years, the guiding effect of highly charged ions (HCIs) through insulating nanocapillary membrane has received extensive attention. It is found that slow highly charged ions at keV energies can be guided along the capillary even when the title angle of membrane is a few degrees and larger than geometry opening angle of the capillary. Initially, Stolterfoht et al. (2002 Phys. Rev. Lett. 88 133201), according to the incident ions deposit positive charges on the capillary surface in a self-organizing manner, proposed scattering and guiding regions to explain this guiding phenomenon. Hereafter, a detailed experiment and simulation performed by Skog et al. (2008 Phys. Rev. Lett. 101 223202) provided clear evidence that the guiding process is actually attributed to the self-organized charge patches formed on the inner capillary walls. HCIs entering into a capillary may hit the surface, leaving their charge on the inner wall of the capillary. When the capillary axis is tilted with respect to the beam incidence direction, a charge patch is formed in the capillary entrance, simultaneously a repulsive electric field is created. After sufficient charge deposition this field is strong enough to deflect the subsequent ions in the direction of the capillary exit. Therefore, the ions are guided through the capillary. The deflection at the charge patch only occurs at relatively large distances from the capillary wall so that the incident charge state of the ions is kept during the passage through the capillary. Further experimental and theoretical studies on various target materials, such as polyethylene terephthalate (PET), polycarbonate (PC), SiO2, and Al2O3 indeed found that a single or a small number of charge patches near the entrance formed in the charge up process dominate the observed oscillatory variations of the ion emission angle and the final guiding process. Besides, measurements and simulations of the steering of swift ions at MeV energies have shown that the transmission mechanism of the high energy ions in a tapered tube is primarily dominated by multiple random inelastic collisions below the surface and the charge patches are not responsible for the transmission process. However, the studies of the transmission of hundreds keV ions through nanocapillaries are still lacking so far. In this work, we observe the evolution of the angular distribution, charge state distribution, FWHM and transmission rate of 100 keV H+ ions incident on a polycarbonate (PC) membrane at +1 tilt angle. It is found that the transmitted particles are located around the direction along the incident beam, not along the capillary axis, which suggests that the mechanism of hundreds keV (E/q~100 kV) protons through capillaries is significantly different from that for the guiding effect of keV protons. We present a qualitative explanation based on the data: that the 100 keV H+ are transmitted by multiple random inelastic collisions below the surface is attributed to the absence of the deposited charges on the surface of the capillary at the beginning of the experiment. After the equilibrium, several charge patches are formed on the inner wall of the capillary, which suppresses the ions to penetrate into the surface of the capillary, while the H+ is transmitted via specular scattering above the surface (or closest to the surface) assisted by the charge patches, and finally is emitted in the incident direction through twice specular scattering. This finding increases the knowledge of charged ions through nanocapillaries, which is conducible to the applications of nanosized beams produced by capillaries or tapered glass within hundreds keV energies in many scientific fields.

Cu thin films are deposited on p-type Si (100) substrates by magnetron sputtering at room temperature. The interface reaction and atomic diffusion of Cu/SiO2/Si (100) systems are studied by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results can be obtained. The onset temperature of interdiffusion for Cu/SiO2/Si(100) is 350 °C. With the annealing temperature increasing, the interdiffusion becomes more apparent. The calculated diffusion activation energy is about 0.91 eV. For the CU/SiO2/Si (100) systems copper silicides are not formed below an annealing temperature of 350 °C. The formation of the copper silicides phase is observed when the annealing temperature arrives at 450 °C.

We have measured the spectra and yields for Ar K and Mo L x-rays from Ar 15+ and Ar16+ ions colliding with molybdenum (Mo) surfaces . The spec tra and yields are measured as a function of the projectile kinetic energy. In t he case of Ar15+ -Mo, both Ar K x-rays and Mo L x-rays are observe d, and the yields of Ar K x-rays are related to the projectile kinetic energ y, the potential energy of hollow atom formed in the interaction, the competitio n of the x-rays emitting from the projectile and the target etc. But in the case of Ar15+-Mo, Mo L x-rays are observed only. The yields of Mo L x- rays induced in both cases increase with the projectile kinetic energy.