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This paper reports that the K x-ray spectra of the thin target (47)Ag, (48)Cd, (49)In and (50)Sn were measured by an HPGe semi-conductor detector in collisions with 84.5 MeV (6)C(4+) ions. Our experiment revealed the K alpha x-ray energy shifts were not obvious and the K beta(1) x-ray energy shifts were about 90 similar to 110 eV. The simple model of Burch et al has been previously used to calculate the K x-ray energy shifts due to an additional vacancy in 2p orbit. The present work extends the model of Burch to calculate the x-ray energy shifts of multiple ionized atoms induced by heavy ions with kinetic energy of MeV/u. In addition to our experimental results, many other experimental results are compared with the calculated values by using the model.

The values of direct double-to-single ionization ratio R of helium atoms induced by Cq+, Oq++ (q = 1–4) ions at incident energies from 0.2 to 8.5MeV are measured. Based on the existing model (Shao J X, Chen X M and Ding B W 2007 Phys. Rev. A 75 012701) the effective charge of the projectile is introduced to theoretically estimate the value of R for the partially stripped ions impacting on helium atoms. The results calculated from our 'effective charge' model are in good agreement with the experimental data, and the dependence of the effective charge on the ionization energy of the projectile is also discussed qualitatively.

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 ratios of transfer ionization (TI) to single-electron capture (SC) cross sections have been measured for the collisions of partially stripped Cq+ ions (q = 1-4) with He. The collision velocity ranges from 0.7 to 4.4v(0) (v(0) is the Bohr velocity). The projectile-ion and recoil-ion coincidence technique is used to separate the processes of TI and SC. The ratios reach the maximum when the velocity is about 3.7 v(0). This can be explained qualitatively based on the two-step mechanism. The experimental results are also compared with the results calculated using the classical trajectory Monte Carlo (CTMC) method. The CTMC results are in agreement with the experimental data basically. The discrepancies in higher velocity region are interpreted by the effective charge effect.

The relative partial cross sections for 13C6+–Ar collisions at 4.15–11.08 keV/u incident energy are measured. The cross-section ratios σ2E/σSC, σ3E/σSC, σ4E/σSC and σ5E/σSC are approximately the constants of 0.51±0.05, 0.20±0.03, 0.06±0.03 and 0.02±0.01 in this region. The significance of the multi-electron process in highly charged ions (HCIs) with argon collisions is demonstrated (σME/σSC as high as 0.79±0.06). In multi-electron processes, it is shown that transfer ionization is dominant while pure electron capture is weak and negligible. For all reaction channels, the cross-sections are independent of the incident energy in the present energy region, which is in agreement with the static characteristic of classic models, i.e. the molecular Coulomb over-the-barrier model (MCBM), the extended classical over-the-barrier model (ECBM) and the semiempirical scaling laws (SL). The result is compared with these classical models and with our previous work of 13C6+-Ne collisions [Chin. Phys. Lett. 23 (2006) 95].

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.

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.

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.

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.

The isotopic bare ion 13C6+ was employed to collide with helium at 4.15–11.08 keV/u. The relative partial cross sections were measured by position-sensitive and time-of-flight coincident techniques. It is shown that the direct-ionization (DI) process can be completely ignored in this region, the transfer ionization (TI) process is the most important double-electron channel, and the probability of the pure double-electron capture (DC) process is quite small. The cross-section ratio of the total double-electron (DE) process (i.e. DC+TI) to the single-electron capture (SC) process is experimentally determined to be approximately a constant of 0.09±0.03 in this region, and this value is obviously smaller than the predictions of the classical over-barrier models and the semi-empirical scaling laws. It is found that the cross-section ratio of pure DC to DE decreases obviously as the projectile velocity increases. Because the pure DC process only comes from the radiation de-excitation following the DC process and are competed by the TI process (comes from the auto-ionization following the DC process), this implies that the population of the two captured electrons depends distinctly on the collision velocity. Comparison with works on Ar16+–He by Wu et al. [Phys. Rev. A 48 (1993) 3617] reveals that the strong projectile-dependent character of the pure DC process exists.

The X-ray emission spectra produced by 2.4-6.0 MeV Xe20+ ions impacting on vanadium surface were measured. The V K-shell X-ray production cross sections were extracted from the experimental yield data and compared with the theoretical predictions of the binary encounter approximation (BEA), the plane wave born approximation (PWBA), and the energy-loss coulomb-repulsion perturbed-stationary-state relativist (ECPSSR). In order to predict reasonably the inner-shell ionization induced by highly charged heavy ions during the asymmetric collisions at near the Bohr velocity, the corrections of BEA model are discussed. It is found that the X-ray production cross section induced by highly charged heavy ions moving at near the Bohr velocity is on the magnitude of 1 barn, which is almost four orders of magnitude larger than that induced by proton. The ECPSSR, which is regarded as the best model to simulate the inner-shell ionization by light ions, may underestimate the experimental data at least three orders of magnitude. The PWBA model presents a prediction to the results on an order of magnitude better than the ECPSSR simulation, but gives a worse tendency than the BEA model. The BEA calculations, corrected both by Coulomb repulsion and effective nuclear charge, present the best agreement with the experimental results. It is proposed, that in the energy region near the Bohr velocity, during the asymmetric collisions of Xe20+ ions with V atoms, the K-shell electron of V is ionized by direct ionization, and that it can be described by the binary encounter process between the xenon ions and the bound electrons. The X-ray production cross section can be simulated by BEA model, but the corrections of Coulomb repulsion and effective nuclear charge must be considered.

In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime (q/v > 1). The results obtained from this approach are in excellent agreement with the available experimental data. A probable scenario of molecular multiple ionization by fast and very high-q projectiles is discussed. The very small computational time required here and the good agreement with the existing experimental data make it a good candidate for studying the multiple ionization of complex molecules under high linear energy transfers.

In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22–6.30 MeV Cq+ ions and 0.25–6.35 MeV Oq+ ions (q = 1, 2, 3, 4) with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q0.60; the energy corresponding to maximum f is about 160q0.60 keV/u.

In this work, the ionizations involving the charge transfer and single capture processes in low charge state ion-atom collisions in low-to-medium energy region, are investigated by the position sensitive and time-of-flight techniques. For a given charge state of the incoming projectiles, the dependence of the ratio RTS of the transfer ionization to the single capture changing with the projectile velocity is obtained, and the conclusion that the ionized electron in the transfer ionization process comes from the outermost sub-shell of the target atom is confirmed by comparing our theoretical results with the experimental data.

This paper presents the measurement results of absolute cross-sections of ion-atom collision in detail. The pure cross-sections of Nei+(i=1—4) induced by C3+ were investigated using coincidence technique. Comparing our experimental results with those of n-body classical trajectory Monte Carlo method, it is found that the changes of pure cross sections with increasing energy have the same trend in the two cases. The causes of discrepancies between them are discussed. The mechanism of multiple-ionization is analyzed. The highly charged recoil ions come mainly from the Auger effect. The electron-electron interaction comes in to effect as the incident energy increases. The cross-sections of all kinds of reactions can be measured in this way using the same equipment and projectile ions can be various within a wide range of energy.

he cross-section ratios for the double-to-single ionization of He associated with no projectile charge change ( R q , q ), single-electron capture ( R q , q -1 ) and single-electron loss ( R q , q +1 ) were measured using coincidence technique. The coincidences resulted from the signals of recoil ions and scattered projectiles. For a given incoming projectile charge state the double-to-single ionization ratios vary strongly with the outgoing reaction channel. It is found that R q , q R q , q +1 R q , q -1 . For direct ionization, R q , q is nearly independent of the incident projectile charge state. However, for ionization associated with single-electron capture and single-electron loss by the projectile, R q , q -1 and R q , q +1 depend strongly on the incident charge state of the projectile. These ionization ratios are interpreted in terms of theories of the atomic polarization effect and the screening and antiscreening effect of the electrons around the core.

This paper studies the X-ray spectra produced by the interaction of highly charged ions of Arq+(q=16,17,18) with metallic surface of Be, Al, Ni, Mo and Au respectively. The experimental results show that the Kα X-ray emerges from under the surface of solid in the interaction of ions with targets. The multi-electron excitation occurred in the process neutralization of the Ar16+ in electronic configuration of 1s2 in metallic surfaces, which produces vacancy in the K shell. Electron from high n state transition to K vacancy gives off X-ray. We find that there is no obvious relation between the shape of X-ray spectra and the different targets. The X-ray yield of incident ions are associated with initial electronic configuration. The X-ray yield of target is related to the kinetic energy of the incidentions.

Rare earth elements Tb, Er and Lu were bombarded by protons with energies of 0.2-1.2 MeV, L-subshell ionization cross sections were obtained. Experimental ionization cross sections were compared with the predictions of the ECPSSR theory.