Mixed Ion Beam Research Articles

Target and detection techniques for the 13N(p, gamma )14O reaction using radioactive ion beams: 13C(p, gamma )14N reaction as a test case.

A feasibility study was undertaken for the measurement of the resonance at ${\mathit{E}}_{\mathit{r}}$=545 keV in the $^{13}\mathrm{N}$(p,\ensuremath{\gamma}${)}^{14}$O reaction, using intense radioactive ion beams. The analog resonance at ${\mathit{E}}_{\mathit{r}}$=512 keV in $^{12}\mathrm{C}$(p,\ensuremath{\gamma}${)}^{14}$N was chosen as a test case, leading to improved knowledge of the resonance parameters. Thin- and thick-target yields were obtained with $^{13}\mathrm{C}$ beams on an extended gas target and a polyethylene foil, respectively. In addition, thin and thick targets of enriched $^{13}\mathrm{C}$ were irradiated with proton beams. Normalization problems arising with mixed ion beams ${(}^{13}$N${/}^{13}$C) are discussed.

The effect of adding gas ions to a beam for deposition of boron nitride films by the ion beam and vapor deposition method

Deposition of boron nitride films was studied by the simultaneous use of ion beam irradiation and vapor deposition. Inert gas (helium, argon) ions were added to a nitrogen ion beam, and the effect on the hardness and the crystallization was studied as a function of gas species, the ratio of inert gas ions/nitrogen ions, and ion energy. Irradiation of mixed ion beams, especially argon plus nitrogen, was effective for crystallization of boron nitride films at an ion energy of 2 keV. The X-ray diffraction pattern from these films was sharp, and its scattering angle agreed with the cubic phase. It became clear that electronic excitation was important in forming the metastable phase, as a result of the relation between the electronic stopping cross section and IR absorption spectroscopy from the cubic phase. The highest value of Knoop hardness of the film was about 4900 kg/mm 2. The cubic phase dominates the hardness of the films.

Sequential SIMS-ISS analysis of oxygen-enhanced secondary ion generation

A special arrangement for ISS signal detection has enabled the sequential analysis by SIMS and ISS to be performed with SIMS apparatus. Using a mixed ion beam of He + and Ar + ions, the He + ions provide ISS signals while the Ar + ions generate secondary ions as usual. We have applied this approach to oxygen-enhanced secondary ion generation. ISS monitors the surface coverage of oxygen on a Ni sample and SIMS the generation of secondary ions, Ni + ions, for different partial pressures of oxygen in the specimen chamber. The present SIMS-ISS analysis has led to the conclusion that the electron tunneling model describes the experimental results with considerable success.

Photon counting method for measuring the current fraction in D2 2+−He + mixed ion sputtering

A photon counting method has been developed for measuring the current fraction in a D 2 +−He + mixed ion beam. Photons produced by feeding Ar-gas into the beam course are counted through 486 nm- and 389 nm-filters, and the current fraction is instantaneously derived from processing the photon yields with a microcomputer. The sputtering yields of Ta and W obtained by the incidence of pure and mixed ion beams at an energy of 25 keV are demonstrated.

Implantation of Intense Pulsed Metallic Ion Beam

The short-duration intense mixed metallic and gaseous ion beams, such as Ti* and N+, produced by the multiplate cnamber with central hole have been used for implantation. The compositions of titanium and nitrogen as a function of depth was determined using Auger electron spectroscopy PHI-550. It is proved that phase transitions of thin layer of steel bombarded by ion beams take place owing to the ion mixing and rapid cooling down of implanted area after melting by the pulsed beams with power density more than 107W/cm2. The effective hardness increase is concluded from microhardness measurements. It is expected that the implantation with pulsed ion beam could open a new way for the significant industrial application.1

Assessments of surface composition and sputtering yield of Au-Cu alloys for Ar + ion bombardment

The possible effect of current density on the outermost surface-layer composition of Au-Cu alloys under keV Ar + ion bombardment at steady state was examined through the mixed-ion beam ISS technique. Measurements of the sputtering yields with a quartz-oscillator mubalance were performed simultaneously. Results of the former measurements indicate that the composition of the outermost atomic layer does not depend on the current density of the primary ion beam in the range from ≈0.5 to ≈90 μA/cm 2, resulting in the enrichment of Au atoms at the outermost atomic layer. The latter have lead to the same result for the total sputtering yield for ion beam intensity ranging from tens of a μA/cm 2 to several hundreds μA/cm 2. Hence both the results lead to the conclusion that the ion enhanced subsurface re-distribution process of the outermost surface atoms under Ar + ion bombardment is much faster in time than the sputter removal rate of atoms from the surface.

Beam Studies of the Ion-Molecule Reaction CO2++D2→DCO2++D

Abstract Reaction cross sections of the reaction CO2++D2→DCO2++D have been measured over the range of the collision energies E=0.4 to 4 eV in the center of mass system. The cross section was obtained from relative values of the reaction Ar++D2→DAr++D by using the mixed ion beam method. The observed cross sections are about half of the Langevin-Gioumousis-Stevenson cross sections and show approximately E−1⁄2 dependence.