Ji-Tian Liu

Mean projected range and range straggling of 50‐ to 400‐keV Hg+ in glass

The range profile of Hg+ implanted at energies from 50 to 400 keV in glass was measured by 4He+ Rutherford backscattering. The measured projected ranges are in good agreement with those predicted by the Biersack model. A marked improvement in the range straggling fit is obtained after considering the second‐order energy loss.

Depth profiles of ion‐implanted fluorine in tin‐oxide films prepared by atmospheric‐pressure chemical vapor deposition

Depth profiles of fluorine in 19F+‐implanted tin‐oxide films have been accurately measured using 19F(p,αγ)16O resonance nuclear reactions at ER=872.1 keV and ER=340.46 keV. A proper deconvolution calculation method was used to extract the true range distribution of implanted fluorine from the experimental excitation yield curves. The range distribution parameters, RP and ΔRp, were thereby obtained and were compared with those obtained by Monte Carlo simulations. The experimental Rp values agree with the Monte Carlo simulation values very well, while the experimental ΔRp values are larger than those obtained theoretically. This phenomenon may be attributed to the enhanced diffusion during the ion implantation.

Range profiles of 50 to 400 keV Hg+ in quartz crystal

Abstract Range profiles of Hg+ implanted at energies from 50 to 400 keV in quartz crystal are measured by MeV 4He+ Rutherford backscattering. The measured projected ranges and range stragglings are compared with the Biersack theory. The result shows that the agreement between the experimental and calculated values is quite good for the projected ranges; after including second order energy loss terms, a better agreement for the range straggling is obtained.

Low-Energy Proton Irradiated Waveguides in KTiOPO4

KTiOPO 4 samples were implanted with 80, 120, and 150 keV H + ions to fluences of 5 × 10 16 ions/cm 2 at room temperature. The modes in KTiOPO 4 samples were measured by a model 2010 prism coupler. From one to a few modes were observed. The number of modes observed depends on the energy. The present results show that the waveguide formation in KTiOPO 4 samples is possible by using low energy H + implantation. Compared with MeV light ion implanted waveguides, it is a low cost, simple and more useful method. Multi-energy implantation is needed to reduce the tunneling loss.

ENERGY SPECTRA OF HE+ IONS PENETRATING THICK BIOLOGICAL TARGETS

Abstract Energy spectra of 500 keV–1MeV He+ ion penetrating 50 μ m – 100 μ m thick seed coat of maize, fruit peel of grape and of tomato, are measured. The results indicate that these thick biological targets, as seen by the penetrating ions, are inhomogeneous, and there are open paths, along which the incident ions can penetrate the targets easily. While most of the incident ions are stopped in the targets, some of the penetrating ions only lose a small fraction of their initial incident energy. The penetration energy spectra show a pure electronic stopping feature. Transmission electron microscope (TEM) micrographs taken from these samples with thickness of 30 μ m indicate that 150 keV electron beam from the TEM can penetrate the thick samples to give very good images with clear contrast. The electronic structures of β−1,4 glucosan molecular chains, which is deemed as the most important constituent of the cell walls of seed coats and peels of fruits, are calculated to show the possible open-path directions which exist in biological samples.

Range profiles of Hg+, Hg2+, and Hg3+ in polymer polyvinylalcohol

Depth profiles of Hg+, Hg2+, and Hg3+ implanted in polymer polyvinylalcohol at energies from 50 to 600 keV are measured by 2.1‐MeV 4He2+ Rutherford backscattering. Based on Biersack’s angular diffusion model, a computer program is written for comparison with the experimental values. The result shows that the measured projected range is in good agreement with the calculated value for first‐order treatment. The experimentally determined range straggling is still higher than the calculated value after considering the second‐order energy loss. The Monte Carlo simulation shows that the Hg profile is not described by an ionization or nuclear damage profile, but rather is described by a classical predicted implantation profile.

Optical and Structural Studies of Proton-Exchanged Waveguides in Z-Cut LiTaO3

Waveguide modes and interference phenomenon were observed using the prism couple technique in the proton-exchanged LiTaO3 waveguides. The loss of the LiTaO3 waveguide was measured by the fiber probe technique. A low loss (0.7 dB/cm) optical waveguide was obtained. The disorder of the Ta atoms in the proton-exchanged layers was detected by Rutherford backscattering/channeling technique.

Electronic stopping powers of Au, Ag, Cu, Pd and Co metals for 19F ions at low velocity

Abstract Electronic stopping cross sections for 80–350 keV 19 F ions in Au, Ag, Cu, Pd and Co films were obtained by range measurement. Depth profiles of 19 F in these materials were measured by 19 F( p , αγ ) 16 O resonance nuclear reaction. A proper deconvolution program was used to extract the depth distribution parameters from the experimental excitation yield curves. The electronic stopping powers were derived through fitting the projected ranges simulated by TRIM/XLL code to the experimentally determined projected ranges. It is shown that the electronic stopping cross sections obtained in this work agree well with those calculated by using TRIM96 as well as previous experimental data and can be described by the four-parameter formulae.

An investigation of range distribution parameters of implanted 19F ions in tantalum

Abstract Depth profiles of fluorine in 19 F + implanted tantalum have been accurately measured using the 19 F(p,αγ) 16 O resonance nuclear reaction at E R = 872.1 keV . In order to extract the range distribution of implanted fluorine from the experimental excitation yield curve, a proper convolution calculated method is presented, from which the range distribution parameters, such as the average projected range R p , the projected range straggling Δ R p , and the skewness of the range distribution SK, were obtained.

Range profiles of Xe+ and Xe2+ of energy 50 to 400 keV in quartz crystal

The Rutherford backscattering technique has been used to determine the depth profile of Xe+ and Xe2+ implanted into amorphized quartz crystal at energies from 50 to 400 keV. Based on Biersack’s angular diffusion model, an efficient method has been developed for comparison with experimental data. The results show that the measured mean projected range is in quite good agreement with calculated value for first‐order treatment. A marked improvement in range straggling is obtained after considering the second order energy loss. Also the results are compared to transport of ions in matter prediction.