Liu Zhao-Yuan

K x-ray relative transition probabilities for 39?Z?68

In this paper we report the measurements of the K x-ray relative transition probabilities as follows: K-beta/K-alpha for the atomic numbers Z = 39, 51, 62, 63, 64, 66, 67 and 68; and K-alpha2/k(alpha1), k(beta1)(1)/k(alpha1), k(beta2)(1)/k(beta1)1, and k(beta3)/k(beta2) for the atomic numbers Z = 62, 63, 64, 66, 67 and 68 as induced by protons at an energy of 3 MeV. The experimental results obtained are then compared with relativistic Hartree-Fock calculations.

The energy loss of 12C and 11B ions in seven elements

Abstract The present work provides previously unpublished stopping powers for 11B and 12C ions in Co, Ni, In, Pd, Gd, Lu and Ta targets in the energy region ∼1–5 MeV. The experimental results were compared with TRIM91 and SRIM96 predictions. The experimental stopping powers for 12C in Co, Ni, In, Pd, and Ta agree with theoretical predictions within several percents, but do not agree well in Gd and Lu. In the velocity-proportional region, a linear dependence of stopping power on the velocity of projectile ion was observed. 4He energy loss was taken as the measure of the sample foil thickness and the obtained thicknesses were confirmed by low energy (

Proton and alpha particle induced L-shell ionization of rare earth and heavy eleme nts

Abstract The L -shell X -ray production cross sections of Ta, Au and Bi by proton and alpha particle projectiles and the L -subshell ionization cross sections of Nd, Dy and Ho bombarded by incident alpha particles are reported. Comparison of these results with ECPSSR calculations are also reported.

L-shell ionization of Eu, Gd, Dy and Ho by 2.25–4.50 MeV incident Li2+ ions

Abstract L -shell X-ray cross sections of Eu, Gd, Dy and Ho have been measured for incident 2.25–4.50 MeV Li 2+ ions. Relative intensity ratios of Eu are reported. All the measured data are expressed graphically in terms of the energy of the projectile and compared with the predictions of ECPSSR theory. A reasonable agreement has been found.

Charge and Energy Dependences of Ionization and Transfer for Helium in Collisions with Fast Charged Projectiles

The classical method within the independent electron model is employed to investigate (i) charge dependences of single and double ionization for helium by various charged ions Aq+ (q = 1 – 8) at impact energies of 0.64 and 1.44MeV/u, respectively, (ii) energy dependences of transfer ionization for helium by 0.5–3 MeV/u A8,9+ ions impact. The Lenz–Jensen model of the atom is applied instead of the Bohr model of the atom, and the impact-parameter dependences are also introduced into the calculations. Satisfactory agreement is found between theoretical and experimental data.

Transfer Ionization of Helium in Collisions with Cq+ and Oq+ (q = 1–3)

Cross-section ratios sigma(TI)/sigma(SC) of transfer ionization (TI) to single capture (SC) of Cq+- and Oq+-He (q = 1 - 3) collisions in the energy range of 15-440 keV/u (0.8-4.2 v(Bohr)) are experimentally determined. It is shown that sigma(TI)/sigma(SC) strongly depends on the projectile velocity, and there is a maximum for E(keV/u)/q(1/2) approximate to 150. Combining the Bohr-Lindhard model and the statistical model, a theoretical estimate is presented, in reasonable agreement with the experimental data when E(keV/u)/q(1/2) > 35.

THE ENERGY LOSS OF 16O IONS IN SEVEN METALLIC ELEMENTS IN VELOCITY-PROPORTIONAL REGION

Abstract The present work provides previously unpublished stopping powers of 16O ions in Ni, Pd, In, Sn, Gd, Lu and Ta in the energy region ∼1.5–5 MeV. The experimental results are compared with TRIM91, SRIM96 and LSS predictions and agree within a few percentages with TRIM91 and SRIM96 calculations. In the present experimental energy region, a linear dependence of stopping powers on velocity of projectile ion was observed. The 4He energy loss is taken as the measure of the sample foil thickness. The effective charge ratios of 16O ions to hydrogen are calculated and compared with theoretical predictions.

Interaction of 18-keV O{sup -} ions with Al{sub 2}O{sub 3} nanocapillaries

The transmission of 18-keV O- ions through Al2O3 nanocapillaries with 50 nm in diameter and 12 mu m in length is studied in this work. By measuring angular distribution of transmitted particles when capillaries were tilted with respect to incident ion beam, two peaks were observed. It is distinguished that one of them is composed by direct transmitted ions and another one is composed by scattered ions. A phenomenon referred to as guiding effect, as found for highly charged ions and low-energy electrons, was observed. When negative ions (18-keV O-) are transmitted through nanocapillaries, most of them were ionized to neutral atoms and even positive ions. The intensity of transmitted particles (O-, O-0, and O+) decreased when the tilt angle increased. In transmitted particles, the fraction of O- declined but that of O-0 and O+ ions grew when the tilt angle grew. Both elastic collision and electrostatic scattering were found in scattered ions.The transmission of 18-keV O{sup -} ions through Al{sub 2}O{sub 3} nanocapillaries with 50 nm in diameter and 12 {mu}m in length is studied in this work. By measuring angular distribution of transmitted particles when capillaries were tilted with respect to incident ion beam, two peaks were observed. It is distinguished that one of them is composed by direct transmitted ions and another one is composed by scattered ions. A phenomenon referred to as guiding effect, as found for highly charged ions and low-energy electrons, was observed. When negative ions (18-keV O{sup -}) are transmitted through nanocapillaries, most of them were ionized to neutral atoms and even positive ions. The intensity of transmitted particles (O{sup -}, O{sup 0}, and O{sup +}) decreased when the tilt angle increased. In transmitted particles, the fraction of O{sup -} declined but that of O{sup 0} and O{sup +} ions grew when the tilt angle grew. Both elastic collision and electrostatic scattering were found in scattered ions.

Classical Study of Transfer and Ionization in A2++He Collisions

A simple model for the direct ionization and transfer ionization probabilities in A2+ +He collisions in a wide projectile energy range is proposed based on the Bohr–Lindhard model and the classical statistical model. The calculated cross sections are in satisfactory agreement with the experimental data available.

Double Electron Processes in Collisions of Partially Stripped Ions Cq+(q = 1−4) with Helium

The multi-electron processes are investigated for 17.9–120 keV/u C1+, 30–323 keV/u C2+, 120–438 keV/u C3+, 287–480 keV/u C4+ incident on a helium target. The cross-section ratios of double electron (DE) process to the total of the single electron (SE) and the double electron process (i.e. SE+DE), the direct double electron (DDI) to the direct single ionization (DSI) as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.