X-ray spectroscopy of hollow argon atoms formed on a beryllium surface

The X-rays induced during interaction of highly charged argon ions with a beryllium surface are reported. It is found that the K shell X-ray yield of single particle during interaction of hydrogen-like argon ions was 3.6 x 10(-3), which is five orders more than that of heliumlike argon ions. Moreover, due to the screening the 2s electron, no K X-ray was emitted during interaction of lithium-like argon ions with the beryllium surface. It is also found that the X-ray spectrum induced by Ar17+ interacting with residual gases is very different from that induced by Ar17+ interacting with the surfaces, that provided an experimental evidence for the existence of the hollow atoms below the surface.

Potentiality of phosphorylation of BRCA1 at Ser 1524 to activate p21 in response to X-ray irradiation

The breast and ovarian cancer susceptibility gene BRCA1 encodes a nuclear phosphoprotein, which functions as a tumor suppressor gene. Many studies suggested that multiple functions of BRCA1 may contribute to its tumor suppressor activity, including roles in cell cycle checkpoints, apoptosis and transcription. It is postulated that phosphorylation of BRCA1 is an important means by which its cellular functions are regulated. In this study, we employed phospho-Ser-specific antibody recognizing Ser-1524 to study BRCA1 phosphorylation under conditions of DNA damage and the effects of phosphorylation on BRCA1 functions. The results showed that 10 Gy X-ray treatment significantly induced phosphorylation of Ser-1524 but not total BRCA1 protein levels. The expression both of p53 and p21 increased after irradiation, but ionizing radiation (IR) -induced activation of p21 was prior to that of p53. The percentages of G0/G1 phase remarkably increased after IR. In addition, no detectable levels of 89 kDa fragment of PARP, a marker of apoptotic cells, were observed. Data implied that IR-induced phosphorylation of BRCA1 at Ser-1524 might activatep21 protein, by which BRCA1 regulated cell cycle, but play no role in apoptosis.

X-ray photoelectron spectroscopy study on GaN crystal irradiated by slow highly charged ions

We utilize slow highly charged ions of Xeq+ and Pbq+ to irradiate GaN crystal films grown on sapphire substrate, and use X-ray photoelectron spectroscopy to analyze its surface chemical composition and chemical state of the elements. The results show that highly charged ions can etch the sample surface obviously, and the GaN sample irradiated by highly charged ions has N depletion or is Ga rich on its surface. Besides, the relative content of Ga-Ga bond increases as the dose and charge state of the incident ions increase. In addition, the binding energy of Ga 3d(5/2) electrons corresponding to Ga-Ga bond of the irradiated GaN sample is smaller compared with that of the Ga bulk material. This can be attributed to the lattice damage, which shifts the binding energy of inner orbital electrons to the lower end.

低速高电荷态重离子辐照的GaN晶体表面X射线光电子能谱研究；X-ray photoelectron spectroscopy study on GaN crystal irradiated by slow highly charged ions

利用低速高电荷态Xeq+和Pbq+离子对在蓝宝石衬底上生长的GaN晶体膜样品进行辐照,并利用X射线光电子能谱(XPS)对样品表面化学组成和元素化合态进行了分析.结果表明,高电荷态离子对样品表面有显著的刻蚀作用;经高电荷态离子辐照的GaN样品表面氮元素贫乏而镓元素富集;随着入射离子剂量和所携带电荷数的增大,Ga—Ga键相对含量增大;辐照后,GaN样品中Ga—Ga键对应的Ga3d5/2电子的束缚能偏小,晶格损伤使内层轨道电子束缚能向低端方向偏移.

低速~(40)Ar~(17+)离子入射金属Be表面发射的近红外光谱线和X射线谱；Infrared Light and X-ray Emissions of ~(40)Ar~(17+) Impacting on Be Surface ；

用速度不同的(动能EK=272和357keV,速度v=1.14×106和1.72×106m/s)的高电荷态离子40Ar17+分别入射金属Be表面,同时测量这种相互作用过程中产生的近红外光谱线和X射线谱。实验结果表明,在低速范围内(速度小于玻尔速度vBohr=2.19×106m/s),速度较小的40Ar17+离子在到达金属的表面临界距离Rc到进入表面(2—3原子层)的进程中,形成了较多的高激发态Ar原子,其退激辐射较强的光谱线,进而验证了经典过垒模型。

Molybdenum L-shell X-ray production by 350-600 keV Xeq+ (q=25-30) ions

Molybdenum L-shell X-rays were produced by Xeq+ (q = 25-30) bombardment at low energies from 2.65 to 4.55 keV/amu (350-600 keV). We observed a kinetic energy threshold of Mo L-shell ionization down to 2.65-3.03 keV/amu (350-400 keV). The charge state effect of the incident ions was not observed which shows that the ions were neutralized, reaching an equilibrium charge state and losing their initial charge state memory before production of L-shell vacancies resulted in X-ray production. The experimental ionization cross sections were compared with those from Binary Encounter Approximation theory. Taking into account projectile deflection in the target nuclear Coulomb field, the ionization cross section of Mo L-shell near the kinetic energy threshold was well described. (C) 2010 Published by Elsevier B.V.

Measurement of the inelastic branch of the stellar O-14(alpha,p)F-17 reaction occurring in the explosive burning in Novae and X-ray busters

The inelastic component of the key astrophysical resonance (1(-), E-x=6.15 MeV) in the O-14(alpha,p)F-17 reaction has been studied by using the resonant scattering of F-17+p. The experiment was done at REX-ISOLDE CERN with the Miniball setup. The thick target method in inverse kinematics was utilized in the present experiment where a 44.2 MeV F-17 beam bombarded a similar to 40 mu m thick (CH2)(n) target. The inelastic scattering protons in coincidence with the de-excited 495 keV gamma rays have been clearly seen and they are from the inelastic branch to the first excited state in F-17 following decay of the 1(-) resonance in Ne-18. Some preliminary results are reported.

Early effects of low dose C-12(6+) ion or X-ray irradiation on human peripheral blood lymphocytes

The aim of this study was to estimate the acute effects of low dose C-12(6+) ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy C-12(6+) ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supematant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-gamma and TNF-alpha in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy C-12(6+) ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) C-12(6+) radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDL (C) 2009 COSPAR. Published by Elsevier Ltd. All rights reserved.

X-ray spectrum emitted by the impact of Xe-129(q+) on Mo surface

We studied the characteristic X-ray spectra produced by the interaction of highly charged ions of X-129(q+) (q =25, 26, 27) with surface of metallic Mo. The experimental result shows that highly charged ions can excite the characteristic X-ray spectra of L-shell of Mo when the beam' s intensity is not more than 120 nA. The X-ray yield of single ion reaches a quantitative level of 10(-8) and increases with the increment of the ion' s kinetic energy and ionic charge (potential energy). By measuring the X-ray spectra of Mo-L alpha(1) the M-level lifetime of Mo atom is estimated by using Heisenberg uncertainty relation.

~(129)Xe~(q+)激发Mo表面产生的X射线谱；X-ray spectrum emitted by the impact of ~(129)Xe~(q+) on Mo surface

研究了高电荷态离子129Xeq+(q=25,26,27)入射金属Mo表面产生的特征X射线谱.实验结果表明,在束流强度小于120nA条件下,高电荷态离子129Xeq+可以激发Mo的L壳层特征X射线谱.单离子X射线相对产额可达10-8量级,特征X射线的相对产额随入射离子的动能和电荷态(势能)的增加而增加.通过Mo原子的Lα1特征X射线谱,利用Heisenberg不确定关系对Mo原子的第M能级寿命进行了估算.

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 47Ag, 48Cd, 49In and 50Sn were measured by an HPGe semi-conductor detector in collisions with 84.5 MeV 6C4+ ions. Our experiment revealed the Kα x-ray energy shifts were not obvious and the Kβ1 x-ray energy shifts were about 90∼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.

Investigation of Degradation Behavior of Polymer on Surface of Film Due to the Existence of Monochromatic X-ray

Degradation and its temperature dependence of poly(methyl methacrylate) (PMMA) in the blend film of PMMA/SAN were investigated via ire-situ X-ray photoelectron spectroscopy(XPS). The results show that thermal degradation of PMMA takes place at 185, 130, 80 degrees C and even room temperature due to the existence of monochromatic X-ray. Furthermore, the degradation rate depends crucially on the experiment temperature.

Effect of annealing on the deformation mechanism of a styrene/n-butyl acrylate copolymer latex film investigated by synchrotron small-angle X-ray scattering

The deformation mechanism of a styrene/n-butyl acrylate copolymer latex film subjected to uniaxial tensile stress was studied by small-angle X-ray scattering. The influence of annealing at 23, 60, 80, and 100 degrees C for 4 h on microscopic deformation processes was elucidated. It was demonstrated that the microscopic deformation mechanism of the latex films transformed gradually from nonaffine deformation behavior to affine deformation behavior with increasing annealing temperature.

Structural evolution of tensile deformed high-density polyethylene at elevated temperatures: Scanning synchrotron small- and wide-angle X-ray scattering studies

The structural evolution of an ice-quenched high-density polyethylene (HDPE) subjected to uniaxial tensile deformation at elevated temperatures was examined as a function of the imposed strains by means of combined synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. The data show that when stretching an isotropic sample with the spherulitic structure, intralamellar slipping of crystalline blocks was activated at small deformations, followed by a stress-induced fragmentation and recrystallization process yielding lamellar crystallites with their normal parallel to the stretching direction. Stretching of an isothermally crystallized HDPE sample at 120 degrees C exhibited changes of the SAXS diagram with strain similar to that observed for quenched HDPE elongated at room temperature, implying that the thermal stability of the crystal blocks composing the lamellae is only dependent on the crystallization temperature.