Synthesis of Bio-organic Molecules of Life Induced by Low Energy Ion Implantation

Gase discharge and ion implantation are respectively used in some simple water solution and solid molecular samples. The implanted samples are analysed by the ^1H nuclear magnetic resonance spectra and the Fourier transform infrared spectroscopy. The results show that some new NO3^- anion, NO2^- anion, dimethyl ether, and ethanol are formed in the water solution samples with nitrogen, methane and carbon dioxide gas discharge. New cyano groups (-CN) and amino groups (-NH2) are formed in the irradiated solid sodium carboxylic sample with N^ ion irradiation. The experimental results present a new way to synthesize small molecules of life by low-energy ion implantation.     

Low Energy Ion Channelling in Single-Wall Nanotubes

Monte Carlo simulation is used to study the low energy He ion channelling in a （17, 0） single-wall nanotube and its rope. The simulation shows that the channelling critical angle ψc = 48E^-1/2 （E is incident energy） for a 1.31-nm-diameter initial beam into the nanotube, while ψc = 45E^-1/2 for the 1.31-nm-diameter initial beam into its rope.     

Formation of High Concentration Cr^4＋ Ion in a PbWO4 Single Crystal

Cr^4＋ ion with tetrahedral symmetry, as found in single crystals of forsterite and YAG, have found application as saturable-absorbors, tunable solid state lasers etc. However, a high concentration of active Cr^4＋ species is difficult to obtain because it is rather unstable in these materials. It is expected that the continuing search for other ahernative hosts will lead to the emergence of new efficient Cr^4＋ -doped lasers.     

Cluster Effects in Deuterium Cluster Ion Implantation on Solids

Explicit expressions of n Bäcklund-Darboux (BD) transformations and corresponding symmetries for generalized KdV (GKdV)equation,were constructed by using factorization of Gelfand-Dickey operator.This extends Lou's recentresult about the BD transformations and non-local symmetries for KdV,Kadomtsev-Petviashvilli equations.As a by-product,we also derive a representation of Wronskian determinant for the GKdV solution.     

Neural Computing in High Energy Physics

Artifical neural networks (ANN) are now widely used successfully as tools for hith energy physics.The paper covers two aspects.First,mapping ANNs onto the proposed ring and linear systolic array provides an efficient implementation of VLSI-based architectures since in this case all connections among processing elements are local and regular,Second.it is discussed algorthmic organizing of such structures on the base of modular algebra whose use can provide an essential increase of system throughput.     

Optimization of Energy Scope for Titanium Nitride Films Grown by Ion Beam-Assisted Deposition

The deposited energy during film growth with ion bombardment, correlated to the atomic displacement on the surface monolayer and the underlying bulk, has been calculated by a simplified ion-solid interaction model under binary collision approximation. The separated damage energies caused by Ar ion, different for the surface and the bulk, have been determined under the standard collision cross section and a well-defined surface and bulk atom displacement threshold energy of titanium nitride （TIN）. The optimum energy scope shows that the incident energy of At＋ around 110eV for TiN （111） and 80eV for TiN （200） effectively enhances the mobility of adatom on surface but excludes the damage in underlying bulk. The theoretical prediction and the experimental result are in good agreement in low energy ion beam-assisted deposition.     

Secondary-Electron Emission Effects in Plasma Immersion Ion Implantation with Dielectric Substrates

Using a dynamic sheath model,we have studied the secondary-electron emission effects at one-dimensional planar dielectric surface in plasma immersion ion implantation.The temporal evolution of the sheath thickness,the surface potential of dielectric,and the ions dose accumulated on the dielectric surface are obtained.The numerical results demonstrate that the charging effects are greatly enhanced by the secondary electron emission effects,so the sheath thickness becomes thinner,the surface potential of dielectric decreases fast and the ions dose accumulated on the dielectric surface significantly increases.     

Effective Stress Reduction in Diamond Films on Alumina by Carbon Ion Implantation

We show the effective stress reduction in diamond films by implanting carbon ions into alumina substrates prior to the diamond deposition.Residual stresses in the films are evaluated by Raman spectroscopy and a more reliable method for stress determination is presented for the quantitiative measurement of stress evolution.It is found that compressive stresses in the diamond films can be partly offset by the compressive stresses in the alumina substrates,which are caused by the ion pre-implantation.At the same time,the difference between the offset by the pre-stressed substrates and the total stress reduction indicates that some other mechanisms are also active.     

Optical Planar Waveguides in KTiOPO4 Crystals by MeV Oxygen Ion Implantation

We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM＇98 （transport of ions in matter） is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation.     

Pulsed Ion Sheath Dynamics in a Cylindrical Bore for Inner Surface Grid—Enhanced Plasma Source Ion Implantation

Based on our recently proposed grid-enhanced plasma source ion implantation(GEPSII) technique for inner surface modification of materials with cylindrical geometry,we present the corresponding theoretical studies of the temporal evolution of the plasma ion sheath between the grid electrode and the target in a cylindrical bore.Typical results such as the ion sheath evolution,time-dependent ion density and time-integrated ion energy distribution at the target are calculated by solving Poisson‘s equation coupled with fluid equations for collisionless ions and BOltzmann assumption for electrons using finite difference methods.The calculated results can further verifty the feasibility and superiority of this new technique.     

Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

By using the isospin-dependent quantum molecular dynamics model,we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size,initial N/Z,isospin symmetry potential and the medium correction of two-body cross sections.We find the effect of the initial N/Z ratio and isospin symmetry potential on stopping is weak.The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections,the equation of state of nuclear matter.Our results show that the behaviour of the excitation function of Qzz/A and R can provide clearer information of the isospin dependence of the medium correction of two-body cross sections.     

Shadow Effect and Its Revisal in Grid-Enhanced Plasma Source with Ion Implantation Method

The implanting voltage, gas pressure and the grid electrode radius are the key parameters influencing the surfacegrid shadow effect that has been observed in our grid-enhanced plasma source ion implantation experiment. To reduce the shadow effect and obtain a corresponding better implantation uniformity of sample surfaces, we needto use lower implanting voltage, higher gas pressure and smaller grid radius. Furthermore, we apply an axialmagnetic field to increase the plasma density inside the tube and to mix the plasma outside the grid, so that theshadow effect of sample surfaces can be weakened.     

Ion－Implanted Waveguides in a Nd^3＋－Doped Silicate Glass

Monomode enhanced-index Nd^3 -doped silicate glass waveguides fabricated by ion implantation are reported.The Nd^3 -doped silicate glass was implanted by 3.0 MeV B^ ions, 3.0 MeV 0^ ions and 4.5 MeV Ni^2 ions,respectively. A prism-coupling method was carried out to measure dark modes in the Nd^3 -doped silicate glassusing a model 2010 prism coupler. The moving fibre method was applied to measure the waveguide propagationloss. After a moderate annealing, the 3.0-MeV B^ -ion implanted waveguide loss is about 3.54 dB/cm; the 3.0-Me V O^ -ion implanted waveguide loss is about 5.36 dB/cm; and the 4.5-MeV the Ni^2 -implanted waveguide lossis about 7.55dB/cm. The results show that with the increasing ion mass, the loss in implanted waveguide isincreased.