Yang Zhi-Hu

Surface Plasmon-Assisted Excitation of Atomic Visible Light Spectral Lines in the Impact of Highly Charged Ions 126Xeq + on Solid Surfaces

We measured the visible light spectral lines of sputtering atoms from solid surfaces of Al, Ti, Ni, Ta and Au which are impacted by 150 keV 126Xeq + (6≤q≤30). It is found that intensities of the light spectral lines are greatly and suddenly enhanced when the charge state of the ion is raised up to a critical value. If assuming that potential energy released from the incident ion due to capturing one electron is enough to excite a surface plasmon, we can estimate the critical charge states and obtain the results very well consistent with the measurements for the above-mentioned target materials. This means that a surface plasmon induced by one electron capture can enhance the excitation of atomic visible light spectral lines in the impact of a highly charged ion on a solid surface.

Studies of K-shell x-ray energy shifts induced by MeV/u heavy ions

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.

L-Shell X-Ray Yields and Production Cross Sections of Zr and Mo Bombarded by Slow Highly Charged Ar16+ Ions

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.

Lifetime Measurements for Electric-Dipole Δn =0 Transitions in the Beryllium-Like Sulfur

We have measured lifetimes of Δn = 0 allowed transitions in beryllium-like sulfur using beam foil spectroscopic techniques. The measured values, derived from analysis of arbitrarily normalized decay curves, are presented and compared with theoretical calculations and previous measurements. Accurate probabilities have been determined by the well-known relationship.

Oscillator Strength for n = 2 Transitions in Highly Ionized Sulfur

Oscillator strength f-values for L-shell transitions in highly ionized sulfur are studied by the beam-foil technique at the HI-13 tandem accelerator in China Institute of Atomic Energy. The lifetimes of the upper levels 2s2p P-1(1)o, 2p(2) S-1(0), 2p(2) P-3(1), 2p(2) P-3(2), 2p(2) P-3(0) of Be-like sulfur are measured to be 129 +/- 4, 81 +/- 5, 165 +/- 7, 159 +/- 8, 176 +/- 11 ps. By using the measured lifetimes, the f-values are calculated to be 0.074, 0.082, 0.060, 0.066, 0.229, 0.056, 0.083, 0.089, 0.028 for the transitions 2s(2)2p(2) P-3(1)-2s2p(3) P-3(1)o, 2s(22)p P-2(3/2)o-2s2p(2) P-2(1/2), 2s2p(2) P-4(3/2)-2p(3) S-4(3/2)o, 2s(2)2p P-2(1/2)o-2s2p(2) D-2(3/2), 2s(2) S-1(0)-2s2p P-1(1)o, 2s2p(1) P-1(o)-2p(2) S-1(0), 2s2p(3) P-0(o)-2p(2) P-3(1), 2s2p P-3(2)o-2p(2) P-3(2) and 2s2p P-3(1)o-2p(2) P-3(0). Most of the experimental results are in agreement with theoretical studies, but differ slightly from the previous experimental data.

Visible Light Emission in Highly Charged Kr17+ Ions Colliding with an Al Surface

We report light emission during the bombardment of Kr17+ ions on an Al surface in the wavelength range 300–700 nm. The three spectral lines of the sputtered Al atoms belong to transitions of Al I 3p 2P°3/2−3d 2D5/2 at 309.26, Al I 3p 2P°1/2−4s 2S1/2 at 394.72 and Al I 3p2 P°3/2−4s 2S1/2 at 396.50 nm. During the neutralization process, the seven spectral lines of Kr I and Kr II from the incident ion of Kr17+ attribute to transitions of Kr I 5p 2[3/2]2−7d 2[1/2]°1 at 616.33, Kr II 5s 2D5/2−5p 2D°3/2 at 410.86, Kr II 5p 4P°5/2−6s 4P5/2 at 430.58, Kr II 4d 2D3/2−4f 2[3]°5/2 at 434.42, Kr II 4d 4D1/2−5p 2S°1/2 at 485.80, Kr II 4p 4S3/2−6s 4P°3/2 at 618.57 and Kr II 5p 4P°3/2−4d 2D5/2 at 656.41 nm. Light emissions of sputtered species depend on energy of the incident ions deposited on the target surface atoms. Light emissions of the neutralized projectiles are formed due to many electrons of the conduction band of the solid surface captured in excited states of the incident ion.

Measurements of the Spectrum of Singly Ionized Argon between 320 and 520 nm

We report beam-foil measurements of the spectrum for Ar II. Totally 56 lines are measured. Most of them are mainly ascribed to 3d-4p, 4s-4p, 4p-4d and 4p-5s resonance transitions. These spectral lines are identified, among which 16 lines are new and accurately measured. Analyses of the spectra are based on a comparison with the other experimental results and calculated values.

Study of n = 2, ?n = 0 transition of Be-, B-, C-, N- and O-like sequence in the beam?foil spectrum of titanium

The foil-excited the spectrum of highly stripped titanium ions between 12?40?nm has been studied. Titanium ions of 80 and 120?MeV were provided by the HI-13 tandem accelerator at the China Institute of Atomic Energy. GIM-957 XUV-VUV monochromator was refocused to get highly-resolved spectra. Our experimental results and the published spectral data of laser-produced plasma show agreement in nearly all cases within ?0.03?nm. The spectra contained some weak or strong lines previously unclassified. These spectral lines mainly belong to 2s2p2 for TiXVIII, 2p3 for TiXVIII, 2s2p3 for TiXVII, 2p64p for Ti XII and 2p63d for Ti XII transitions.

X-Ray Emission from Zr, Mo, In and Pb Targets Bombarded by Slow Highly Charged Arq+(q = 13,14,15,16) Ions

We study the L x-ray emission from Zr, Mo and In targets and M x-ray emission from Pb target under bombardment of low energy Arq+ (q = 13,14,15,16) ions. The relative x-ray yields were measured in the projectile kinetic energy range 210-360 keV. It is found that the relative x-ray yields from Zr, Mo and Pb targets increase with the increasing projectile kinetic energy for Ar14+ and Ar16+ projectiles and depend on the potential energy of the projectile remarkably.

Spectra of highly ionized nickel

The spectrum of highly ionized nickel in the region 12-40nm was studied by means of the beam-foil method. Nickel ions of 45 and 70MeV were provided by the HI-13 tandem accelerator at China Institute of Atomic Energy. Numerous lines attributed to Ni XIII to XX transitions have been identified, and eighteen lines of them were newly measured.