^60Coγ射线辐照降解吡虫啉稀水溶液

采用^60Coγ射线辐照降解吡虫啉稀水溶液,并对辐照前后的水样进行高效液相色谱（HPLC）、离子色谱（IC）和高效液相色谱-质谱联用（HPLC—MS）等检测。实验结果表明,吡虫啉的降解率随吸收剂量的增大而不断增大,当吸收剂量为1．56kGy时,降解率达到100％;吡虫啉的辐照降解产物包括Cl^-1、NO2、NO3-和NH4^＋四种无机产物,2-chloro-5-imidazol-1-ylmethyl-pyridine、1-（6-chloro-pyridin-3-ylmethyl）-1,3-dihydro—imidazol-2-ylideneamine、单羟基化吡虫啉和双羟基化吡虫啉4种有机产物。强氧化性的·OH容易进攻吡虫啉分子中的C=N键、N-N键、C—Cl键以及亚甲基中的C—H键。     

MeV离子辐照拟南芥的萌发规律研究

利用不同能量的F离子和H离子分别辐照拟南芥干种子,通过种子发芽率实验研究了低能离子生物效应与离子种类、离子能量和辐照注量之间的关系。实验结果表明,H离子的辐照效率高于F离子;F离子辐照的种子发芽率曲线,随F离子注量的增加,均呈现先下降后升高再下降的马鞍曲线形状,达到马鞍峰值需要的注量随离子能量的增加而减少。文中对上述现象的可能机理进行了讨论。     

Effect of the displacement damage from argon ion irradiation on the synergistic effect of helium–hydrogen in tungsten

The effect of argon ion pre-irradiation on helium and hydrogen ion irradiation was investigated in tungsten. At the same time, comparative experiments were carried out on the irradiation of helium and hydrogen ions in tungsten. Without the argon ion irradiation, the energy of 35 keV hydrogen ions mainly accelerated the coalescence of defects created by the 60 keV helium ions, the irradiation damage degree increased with hydrogen ion fluence increasing. With the argon ion irradiation, lots of voids were created by argon ion irradiation, which increased the helium and hydrogen retention and the synergistic effect of helium–hydrogen in tungsten. In the same hydrogen fluence, the surface damage degree with argon ion pre-irradiation was higher than that without argon ion pre-irradiation.     

One-step phenol production from a water–toluene mixture using radio frequency in-liquid plasma

The objectives of this research were to understand the process of converting toluene into phenol in a one-step process directly from a water–toluene mixture using the plasma in-liquid method.Experiments were conducted using 27.12 MHz radio frequency(RF) in-liquid plasma to decompose a solution of 30% toluene. Based on the experimental results as evaluated using gas chromatography–mass spectrometry(GC–MS), along with additional analysis by the Gaussian calculation, density functional theory(DFT) hybrid exchange–correlational functional(B3LYP)and 6-311 G basis, the phenol generated from toluene was quantified including any by-products.In the experiment, it was found that OH radicals from water molecules produced using RF inliquid plasma play a significant role in the chemical reaction with toluene. The experimental results suggest that phenol can be directly produced from a water–toluene mixture. The maximum phenol yields were 0.0013% and 0.0038% for irradiation times of 30s and 60s,respectively, at 120 W.     

Reactive sputtering of simple condensed gases by keV ions II: Mass spectra

Condensed gas layers of H₂O, NH₃ and CO at 15–20 K have been bombarded by 6 keV H⁺₂ and 3 keV He⁺ and Ar⁺ ions. Mass spectra of the neutral species sputtered from these layers have been measured. There is a substantial yield of products which originally were not in the target material, and which have thus been formed in chemical reactions induced by the ion bombardment. The relative yields of some of the products have been found to increase with decreasing incident ion mass. This is mainly attributed to the larger amount of energy deposited by electronic stopping in such situations. From CO a nonvolatile residue is left after ion irradiation. From a layer of H₂O frozen on top of the CO-residue H₂CO was detected.     

Reactive sputtering of simple condensed gases by kev ions III: Kinetic energy distributions

Condensed gas layers of H₂O, NH₃ and CO at 15–20 K have been bombarded by 6 keV H⁺₂ and 3 keV He⁺ and Ar⁺ ions. Mass spectra of the neutral species sputtered from these layers have been measured. There is a substantial yield of products which originally were not in the target material, and which have thus been formed in chemical reactions induced by the ion bombardment. The relative yields of some of the products have been found to increase with decreasing incident ion mass. This is mainly attributed to the larger amount of energy deposited by electronic stopping in such situations. From CO a nonvolatile residue is left after ion irradiation. From a layer of H₂O frozen on top of the CO-residue H₂CO was detected.     

Ion irradiation—induced structure damage to botanic samples using the ion transmission energy spectrum

1 INTRODUCTIONThe new aPplications of low energy heavy ion beam in irradi4ted botanical materialswere studied in recellt yeaxs. The beaminduced mutation effect on crop seeds has causedthe attention of physicist and biologists.[1l:] FOr examPle, 1ow energy ions can induceremarkable mutation to rice seeds.[3] There are many special phenomena when heavyions bombard botanic sW1e due to its special structure. Some studies showed that tllepenetration depths of some ions were far larger than t…     

Effect of Auger neutralization on yields of He ions backscattered and alkali ions sputtered from the surface of alkali halides by keV He ion impact

The yields of ions and neutrals backscattered and alkali ions sputtered from LiF crystals by keV He⁺ ion impact have been measured by means of the coaxial impact collision ion scattering spectroscopy in time of flight analysis mode using the charging-up effect. It is found that as the charging-up potential increases due to continuous irradiation of the pulsed ion beam, the time of flight of the He⁺ ions backscattered shifts toward the shorter time, while that of the neutrals backscattered shifts toward the longer, and that of Li ions sputtered also shifts much more clearly toward the shorter. The charging-up potential has been estimated as a function of irradiation time of the pulsed ion beam from the time of flight data and the ion to neutral ratio in the backscattering yields is estimated to be about 0.15. The mechanisms for ionization on He and sputtering of alkali ions are discussed in terms of charging-up and trion (bihole and electron) produced by Auger neutralization of keV He⁺ ions at the target surface.     

Study of proton radiolysis of solid uracil film

In order to understand the molecules mechanism of ion irradiation,which has been widely used in many fields such as cancer therapy,uracil,one of the bases of nucleic acid.was chosen in the low energy ion radiolysis research.The solid uracil films with mass thickness of 0.314mg/cm^2 were irradiated by 200keV H^ ions .The experimental results show that 200keV H^ ions are effective in decomposition of uracil molecules.One of the decomposition products,5,6-dihydro-uracil,was separated by high performance liquid chromatograph (HPLC) and detected using an UV-light detector.Its yield increases first but then decreases as the ion dose increasing.In addition,the mechanism of uracil decomposition and 5,6-dihydro-uracil formation was also disucssed.     

Enhancement of etch rate for preparation of nano-sized ion-track membranes of poly(vinylidene fluoride): Effect of pretreatment and high-LET beam irradiation

We investigated how pretreatment and high-LET beam irradiation affected the ion-track dissolution rate in poly(vinylidene fluoride) (PVDF) films by SEM observations and conductometric analysis in order to develop the preparation methodology of nano-sized ion-track membranes. PVDF thin films irradiated with four types of ion beams were exposed to a 9 mol/dm³ KOH aqueous solution after their storage in air at 120 °C. This heating treatment was found to enhance the etch rate in the latent track, both in the inner core and outer halo regions, without changing that in the bulk, probably due to the formation of parasitic oxidation products facilitating the introduction of the etching agent to improve the etchability. Additionally, the irradiation of heavier higher-LET ions, causing each track to more activated sites (like radicals), was preferable for achieving effective etching.     

Determination of ion fraction and energy analysis of sputtered particles from deuterium bombarded surfaces

Ion energy distributions and sputtering yields have been measured in the presence of various background gases for deuterium, helium and argon ions in the 1–40 keV energy range. Alteration of the surface chemistry of hydride forming metals such as Ti, Y and V by exposure to hydrogen has a significant effect on the charge state of the sputtered particles. Under conditions likely to prevail in plasma devices and possible reactors, the ion/neutral fraction may be drastically increased, reaching ~41% for Ti. Such large ion fractions for metal targets have been previously observed only by sputtering with oxygen ions and present the possibility of improved impurity control in plasma devices. Both gas adsorption and recoil implantation are involved in the mechanism determining the ion fraction of sputtered products.     

Nanostructuring of BaF2 (1 1 1) surfaces by single slow highly charged ions

The creation of surface nanostructures in BaF₂ (1 1 1) surfaces was studied after irradiation with slow highly charged Xe ions from the Dresden-EBIT (electron beam ion trap). After irradiation, the crystals were investigated by scanning force microscopy (SFM). Using specific ion parameters, the topographic images show nanohillocks emerging from the surface. Additionally, we used the technique of selective chemical etching to reveal the lattice damage created by ion energy deposition below and above threshold needed for surface hillocks formation. The role of both potential and kinetic energy as well as a comparison with results for swift heavy ion irradiations of BaF₂ single crystals are presented.     

Sputtering of materials by H+, D+, T+ and He+ Ions

The sputtering yields of various materials by H⁺, D⁺, T⁺, He⁺ ions were calculated using the theoretical dependence of sputtering yields on energy and ion mass and taking into account experimental sputtering yield values, whenever available, as measured for H⁺, D⁺, T⁺, He⁺ ions.     

A molecular dynamics study of the clustering of implanted potassium in multiwalled carbon nanotubes

We have studied the low energy irradiation of carbon nanotubes (CNT) with K ions using classical molecular dynamics simulations with analytical potentials. The studied CNTs had diameters of about 0.5–1.2 nm and single or multiple walls. The average penetration depth and probabilities to introduce an impurity atom into CNT were studied with simulations on irradiating the CNT with single K ion. The number of potassium clusters, their average sizes and the damage produced into the CNT due to the irradiation were studied using multiple K ion irradiations. We found that the K ions are mobile in CNTs right after the implantation event and that they cluster together. For CNTs with 1–3 coaxial tubes, the highest ratio of K atoms in clusters per total number of K ions was obtained by using an irradiation energy of about 100 eV. Also the least damage per K ion was found to be produced into the CNT with this energy when those energies high enough for the ion to penetrate the outermost wall of the CNT were considered.     

Enhanced field emission from nano-graphite coated carbon nanotubes

An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrogen ion irradiation increased, and the turn-on field and the threshold field decreased significantly. The structure characteristic revealed by transmission electron microscopy demonstrates that CNTs are coated by nano-graphite particles after being treated with low energy carbonhydrogen ion and that there are large quantities of defects and grain boundaries in the coated layer. It is considered that the coating layer can decrease the effective surface work function of CNTs and correspondingly increase field emission. In addition, the defects, the grain boundaries and the C-H dipoles forming in the process of the low energy ions irradiation can effectively enhance the field emission.     

中能氩离子束辐照麦胚自由基的ESR研究

用ＥＳＲ波谱技术，研究了室温下中能氩离子辐照小麦种子胚部产生的自由基，观察了自由基的稳定性，实验结果表明，种子中自由基浓度随种子含水量线性增加，自由基浓度随辐照剂量增加，然后趋于饱和，讨论了自由基与种子损伤的关系。根据实验数据和 自由基扩散理论估算了自由基在麦胚中扩散距离。     

Isotopic composition of boron secondary ions as a function of ion-beam fluence

We have examined the effects of target mass on sputtered material using 100 keV argon and neon to sputter an elemental target comprising the two naturally occurring isotopes of boron. At low beam fluences (≈ 1 × 10¹⁵ions/cm²) a light-isotope secondary enhancement is observed relative to steady-state secondary ion yields collected at higher beam fluences. The enhancement (46.1%o for Ne⁺ irradiation and 51.8%o for Ar⁺ irradiation) is large compared to the predictions of analytical theories and is independent of variations in surface potential, chemical effects, and surface impurities. This effect is consistent with an explanation based on an energy and momentum asymmetry in the collision cascade.     

Reaction kinetics of radiation-induced defects in vitreous silica under ion beam irradiation

The production behavior of radiation-induced defects in vitreous silica was studied by an in-situ luminescence measurement technique under ion beam irradiation of He⁺. The luminescence intensity of oxygen deficiency centers (ODCs) at 460 nm was observed to vary with irradiation time reflecting the accumulation behavior of the ODCs. The luminescence intensity increased after the start of irradiation and then decreased at room temperature, while it increased rapidly to a constant value at higher temperatures. Some differences were observed due to different OH contents in silica. The observations were analyzed by considering the production mechanisms and kinetics of the radiation-induced defects.     

低能离子辐照的刺激效应模型

注入离子的质量沉积产物对细胞修复等具有刺激作用。在综合考虑低能离子辐照的能量效应和质量沉积效应的基础上,推导出低能离子辐照下生物体的存活率公式及染色体畸变率和细胞突变率公式,对低能离子辐照下多种生物效应（如特殊的“马鞍型”存活率剂量效应等）作出了很好的拟合。