keV量级的N+注入引起的氨基酸分子损伤

利用电子顺磁共振和红外光谱研究了ｋｅＶ级Ｎ＾＋注入到几种固态氨基酸样品中引起的分子结构损伤。结果表明,这一注入导致了分子的严重损伤：分子结构解体,红外吸收普遍降低;产生了大量的碎片,其中自由基碎片的类型和数量随注入离子的剂量发生显著变化;损伤碎片重组,形成了新的化学组合,表现出新的红外吸收峰。     

25keV As^＋大倾斜角注入的损伤分析

通过２５ｋｅＶ的Ａｓ＋注入硅中．用背散射沟道分析技术和椭圆偏振光测量技术分析了在倾斜角分别为７°、１５°、３０°、４５°和６０°时的损伤分布，揭示了大倾斜角注入在注入能量较低时的一些物理现象．     

低能N+注入诱导大肠杆菌的16S rRNA遗传进化

为了探究低能N⁺注入对大肠杆菌16S rRNA遗传进化与耐药表征的作用,本研究利用低能N⁺注入诱变筛选耐药大肠杆菌,通过基因组de novo测序获得其16S rRNA基因序列,通过K-B法检测诱变菌株的耐药特征。结果共诱变获得了25株耐药菌株,其中5株诱变菌16S rRNA基因分别出现片段缺失,点突变(A257C),GC%含量增高,二级结构变异,并获得多药耐药特性。结果提示：低能N⁺注入可以驱动大肠杆菌16S rRNA基因的随机突变和进化,进而调节耐药基因从头合成或变异,使大肠杆菌耐药性改变。     

低能重离子注入麦胚引起深层细胞损伤的一种可能机制

讨论了低能重离子注入麦胚造成深层细胞损伤主要是注入离子与小麦组成各元素发生相互作用后的次级过程中产生了特征Ｘ射线。以能量较高（３。５８９ｋｅＶ），强度相对贡献较大的钾元素为例，当强度减弱至原来的２＾－＾１＾０时，其穿越麦胚深度可达３７０μｍ，可谓是“长射程”。小麦种子在深层能受到低能离子注入的影响，可能正是由于这种次级过程的“长射效应”。     

V＋C共注入对不锈钢表面机械性能改善的研究

采用改进的MEVVA源阴极对不锈钢进行了V +C共注入 ,并做了X射线衍射分析 ,硬度和磨损实验。V +C共注入剂量为 1× 10 17— 8× 10 17cm- 2 ,能量为 80keV。实验结果表明 ,V +C共注入后不锈钢表面的机械性能得到了改善 ,表面硬度增加了 16%— 82 % ,而耐磨性则是未注入样品的 1.4— 2 .2倍 ,最好的结果均从剂量为 4× 10 17cm- 2 的样品中得到。X射线分析表明 ,V +C共注入后在不锈钢表面形成了新相FeV ,Cr2 VC2 ,VC ,Cr2 3 C6 和Fe5C2 。这些新相在提高表面硬度和耐磨性方面起了重要作用。这些结果与V +C双注入同种不锈钢所得结果进行了比较 ,比较结果表明共注入方法对材料表面改性比双注入方法更有效。     

硅中注入BF^＋2辐射损伤的反常行为

借助离子束背散射和沟道技术结合透射电子显微镜分析，研究了在３００Ｋ和７７Ｋ下硅中注入ＢＦ＾＋２辐射损的反常行国。结果发现ＢＦ＾＋２注入在硅中产生的损伤层或无定形层情况区别于其它较重离子注入。在３００Ｋ下注入时，硅中引入的两个损伤峰，其中一个位于离子入射的平均投影射程附近，另一个则在近表面，在７７Ｋ下注入时，硅中引入的损伤层或无定形层首先出现在表面，随注入剂量的增加，地锭形层向硅体内延伸。     

Research into keV N irradiated glycine

A set of experimental results obtained concerning glycine irradiated with N⁺ at an energy of 30 keV is obtained. The techniques used to get insight into the induced products are mass spectrometry, infrared spectrometry and ultraviolet visible spectrometry. The main non-volatile stable products obtained have been identified by combined gas chromatography mass spectrometry (GC/MS) and other modern instrumental analysis. The results were compared with those obtained with γ rays and show that more kinds of products are formed in keV ion irradiation. The combination of the implanted ion with glycine and nuclear collisions were thought to be probable processes to form the products. Some possible implications of the results are also suggested.     

Damage analysis of benzene induced by keV fullerene bombardment

Molecular dynamics computer simulations have been used to investigate the damage of a benzene crystal induced by 5 keV C₂₀, C₆₀, C₁₂₀ and C₁₈₀ fullerene bombardment. The sputtering yield, the mass distributions, and the depth distributions of ejected organic molecules are analyzed as a function of the size of the projectile. The results indicate that all impinging clusters lead to the creation of almost hemispherical craters, and the process of crater formation only slightly depends on the size of the fullerene projectile. The total sputtering yield as well as the efficiency of molecular fragmentation are the largest for 5 keV C₂₀, and decrease with the size of the projectile. Most of the molecules damaged by the projectile impact are ejected into the vacuum during cluster irradiation. Similar behavior does not occur during atomic bombardment where a large portion of fragmented benzene molecules remain inside the crystal after projectile impact. This “cleaning up” effect may explain why secondary ion mass spectrometry (SIMS) analysis of some organic samples with cluster projectiles can produce significantly less accumulated damage compared to analysis performed with atomic ion beams.     

40 keV He离子注入单晶Si引起的损伤效应研究

室温下使用40 keV He离子注入单晶Si样品到剂量5×1016 cm-2,分别采用透射电子显微镜(TEM)、热解吸谱仪(THDS)、光致发光谱仪(PL)详细地研究了随后热处理过程中He注入空腔的形成、He气体原子的热释放以及注入损伤引起的光致发光特性.结果表明,He离子注入及随后的高温热处理会在单晶Si中产生宽度约为220 nm的空腔带,同时伴随着He气体原子从注入产生的缺陷中释放出来.He气体原子的热释放可以明显地分为两个温度阶段,分别对应于He原子从小的空位型缺陷和大的空腔中的热释放.此外,He离子的注入还会在单晶Si中产生明显发光中心,导致了波长约为680 nm和930 nm的两个光致发光带.该光致发光带的出现可能跟He离子注入及退火过程中产生的纳米Si团簇有关.     

离子束辐照甜叶菊种子的当代生物学效应

本文用20keVN+离子束处理甜叶菊种子,注量分别为100×2500、400×2500和1000×2500N+/cm2,研究不同注量下甜叶菊种子发芽势以及发芽率的变化情况,并分析各处理组间差异。经统计分析,不同注量的甜叶菊种子发芽势和发芽率在α=0.05水平上差异显著。结果表明,随注量增大,发芽势和发芽率均呈先升后降趋势;注量为400×2500N+/cm2时,发芽势和发芽率达最高。     

氮离子注入柠檬酸生产菌的诱变选育

用15keV氮离子注入对柠檬酸生产菌进行诱变选育,对该低能离子与微生物间的作用规律进行了初步探索,并获得三株高产突变菌株。其中,以木薯为底物的突变菌株的柠檬酸产率提高14．2％,以玉米粉为底物的两株突变菌株的柠檬酸产率分别提高15．9％和17．0％,经多次传代实验表明,这三种突变菌株均有较好遗传稳定性。     

N+离子注入对Aspergillus sp.产原果胶酶的诱变效应

原果胶酶是一种具有广泛应用前景的工业酶类,为获得高活性原果胶酶的菌株,用能量为15 keV、注量为20×2.6×1013-180×2.6×1013cm-2的N+注入原果胶酶产生菌黑曲霉Aspergillus sp.XZ-131的成熟孢子,其存活率曲线为典型的"马鞍型"剂量-效应曲线.经筛选确定高产诱变菌株Z-25,经传代培养,高产性状稳定遗传.发酵过程中比原始菌株提前24 h进入生长旺盛期,随后在稳定期期间大量产酶,发酵至72 h时酶活性达到最高,比原始菌株提高了179%,每克干细胞性比原始菌株提高了84%.     

380 keV proton irradiation effects on photoluminescence of Eu-doped GaN

The effect of 380 keV proton irradiation on the photoluminescence (PL) properties has been investigated for undoped and Eu-doped GaN. As the proton irradiation exceeds , a drastic decrease of PL intensity of the near band-edge emission of undoped GaN was observed. On the other hand, for Eu-doped GaN, the PL emission corresponding to the ⁵D₀→⁷F₂ transition in Eu³⁺ kept the initial PL intensity after the proton irradiation up to . Present results, together with our previous report on electron irradiation results, suggest that Eu-doped GaN is a strong candidate for light emitting devices in high irradiation environment.     

Study of surface activation of PET by low energy (keV) Ni and N ion implantation

Polyethyleneterephthalate (PET) has been modified by 100 keV Ni⁺ and N⁺ ions using metal ion from volatile compound (MIVOC) ion source to fluence ranging from 1 × 10¹⁴ to 1 × 10¹⁶ ions/cm². The increasing application of polymeric material in technological and scientific field has motivated the use of surface treatment to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionization radiation, it suffers damage leading to surface activation depending on the type. The surface morphology was observed by atomic force microscopy (AFM). That show the roughness increases with fluence in both the cases. The Ni particles as precipitation in PET were observed by cross-section transmission electron microscopy (XTEM). The optical band gap (E_g) deduced from absorption spectra; was calculated by Tau’c relation. Raman spectroscopy shows quantitatively the chemical nature at the damage caused by the Ni⁺ and N⁺ bombardment. The ration of I_D/I_G shows graphite-like structure is formed on the surface. A layer of hydrogenated amorphous carbon is formed on the surface, which has confirmed by XPS results also.     

Implantation of anatase thin film with 100 keV Fe ions: Damage formation and magnetic behaviour

We have investigated the damage morphology and magnetic properties of titanium dioxide thin films following implantation with Fe ions. The titanium dioxide films, having a polycrystalline anatase structure, were implanted with 100 keV ⁵⁶Fe⁺ ions to a total fluence of 1.3 × 10¹⁶ ions/cm². The ion bombardment leads to an amorphized surface with no indication of the presence of secondary phases or Fe clusters. The ion-beam induced damage manifested itself by a marked change in surface morphology and film thickness. A room temperature ferromagnetic behaviour was observed by SQUID in the implanted sample. It is believed that the ion-beam induced damage and defects in the polycrystalline anatase film were partly responsible for the observed magnetic response.