H3+团簇离子的实验研究

报道了H+ 3 离子通过碳膜后 ,在其中产生的各种微量产物的测量结果 ,讨论了离子与碳膜作用中的电荷交换过程 ,分析了这些微量产物的形成机理 ,证明在产物的形成中电荷交换过程起关键作用 ,研究了离子与碳膜作用中的团簇效应和尾流效应. The yields of H -, H, H 2, H + 2 and H + 3 for H + 3 ions passing through carbon foils have been measured respectively.The results show that the charge exchange process in the interaction of Hydrogen ions with carbon foils plays a key role in the formation of these products. The cluster effects and wake effect of H + 2 and H + 3 ions in carbon foils are also discussed.     

H3+团簇离子与固体相互作用

报道了H3+团簇通过碳膜对产生的各种产物的测量结果.分析讨论了三原子离子团簇与固体相互作用中的电荷交换过程.证明在产物的形成中,电荷交换过程起关键作用.分析研究了H3+团簇与固体作用中的团簇效应和尾流效应. 关键词： H3+团簇 电荷交换 团簇效应 尾流效应     

MeV氢微团簇离子与固体介质的电荷交换

利用静电加速器提供的0.6—1.8MeV的H⁺，H⁺₂，H⁺₃离子，轰击不同厚度的碳膜，分别测量这些离子通过碳膜后各种产物的产额. 得到了不同能量的H⁺通过碳膜后中性原子H和负离子H^-的产额随入射质子速度的变化关系；分别得到能量为1.2MeV,1.8MeV的H⁺₂，H⁺₃团簇离子通过不同厚度碳膜的透射产额及其与团簇离子在碳膜中驻留时间的关系；对结果进行了理论分析与讨论. 关键词： 团簇离子 电荷交换     

HD2+通过超薄碳膜的"尾流"效应

快分子离子穿过固体时会产生库仑爆炸(Coulomb Explosion),尾流效应是库仑爆炸中的一个显著特性.HD2 的爆炸能谱在实测中发现了一些引人注目的特性:1)H 的尾流效应特别显著;2)H 的能谱结构非常类似HeH 中H 的能谱;3)尾流效应在D 的能谱中体现得很弱.这些特性对分析了解HD2 的结构和物理化学性质有很大的帮助.本文依照“尾流”效应(Wake Effect)的等离子体模型,将爆炸中两个D 产物的尾流场近似认为一个He 的尾流场,模拟计算了1.4977 MeV HD2在100 nm碳膜中分解后0°方向的能谱形式.给出了相同条件下的实验结果,得到了非常接近的结果,并将两者作了比较和分析.文中同时给出了D 的实验能谱,对D 的尾流效应相对较弱作了分析,指出对不同产物分辨的差异、产物的非直线运动等是造成D 尾流效应弱的原因.     

相邻类氢离子电离能关系的研究

根据类氢离子电离能的实验值和相邻元素电离能的相关约束方程,定量地建立了各元素类氢离子电离能与核电荷数的较为精确的递推关系.其推算结果与实验值的相对误差小于0.001%,与相对论自洽场方法计算的结果相比,其相对误差也小于0.001%.     

H^＋n团族形成的Guo氏理论与结构计算

对于Ｈ＾＋ｎ的形成，Ｇｕｏ清泉教授指出，可先以Ｈ＾＝离了为中心瞬时地分别与周转个Ｈ原子相互作用，形成中心氢核同周围氢核间的（ｎ－１）个瞬时单电子键，这些单民子键围绕中心转动共振，从而使Ｈ＾＋吸引周围（ｎ－１）个Ｈ原子形成Ｈ＾＋ｎ团簇。     

类氢离子的电荷剥离截面

使用双撞近似和托马斯－费米近似计算了类氢离子Ｌｉ＾２＋和Ｃ＾５＋与中性原子Ｈ和Ｈｅ碰撞的电荷剥离截面。计算结果表明,总截面主要处在０．３５－１０的速度范围,这些载面与ＴｏｓｈｚｏＳｈｉｒａｉ等人计算的结果符合得较好。     

超短脉冲强激光与团簇的相互作用

超短脉冲强激光与团簇的相互作用已被证明能够产生能量高达ＭｅＶ量级的高能离子和中子以及非常强的Ｘ射线辐射。广阔好原子团簇在超短脉冲强激光场的作用下的加热、电离和膨胀等机制,对这种相互作用的深入研究可能会对激光核聚变和Ｘ射线激光等应用领域产生重大影响。     

C20离子团簇在氧化物中穿行时库仑爆炸过程的理论研究

本文研究了C20团簇在几种金属氧化物（Al2O3，SiO2）中穿行时发生的库仑爆炸过程，采用线性介电响应理论，并结合Memfin形式的介电函数，得到了团簇中各组成离子的空间感应势，其中组成团簇中各组成离子的电荷分布情况由Brandt-Kitagawa有效电荷理论模型来描述。通过求解运动方程得到离子团结构随时间的演化过程，并采用Monte Carlo方法模拟了爆炸过程中的多重散射现象。我们发现，尾流效应使团簇的空间结构和电荷分布呈现非对称性。     

C20离子团簇在氧化物中穿行时库仑爆炸过程的理论研究

研究了C20团簇在几种金属氧化物(Al2O3,SiO2)中穿行时发生的库仑爆炸过程.采用线性介电响应理论,并结合Mermin形式的介电函数,得到了团簇中各组成离子的空间感应势,其中组成团簇中各组成离子的电荷分布情况由Brandt-Kitagawa有效电荷理论模型来描述.通过求解运动方程得到离子团结构随时间的演化过程,并采用Monte Carlo方法模拟了爆炸过程中的多重散射现象.我们发现,尾流效应使团簇的空间结构和电荷分布呈现非对称性.     

Study on charge equilibration time of highly charged ions in carbon foils

Charge state distribution of 0.8MeV/u uranium ions after transmission through a thin carbon foil has been studied. It is observed that the charge state distribution is equilibrated after the uranium ions have passed through a 15 $\mu $g/cm$^{2}$ carbon foil. The equilibrated average charge state is 33.72 and the charge equilibration time of uranium ions in carbon foil is less than 5.4fs.     

Study on charge equilibration time of highly charged ions in carbon foils

Charge state distribution of 0.8MeV/u uranium ions after transmission through a thin carbon foil has been studied. It is observed that the charge state distribution is equilibrated after the uranium ions have passed through a 15μg/cm^2 carbon foil. The equilibrated average charge state is 33.72 and the charge equilibration time of uranium ions in carbon foil is less than 5.4fs.     

Bombarding insulating foils with highly energetic ions

Insulating (MYLAR), semi-insulating (MYLAR-Au) and conducting foils have been bombarded by very energetic 64 MeV u^{?1 78}Kr³²⁺ ions. The velocity spectra of fast electrons emitted in the backward and forward directions have been measured and analyzed as a function of the elapsed time in the run. A shift of binary encounter and convoy electrons emitted in the forward direction toward lower velocities has been observed with insulating targets. No such shift occurs with metallic targets. The surface potential evolves with time (i.e. ion fluence) both at forward and backward emission angle. It is shown that strong bulk charging of insulating targets leads to a positive potential as high as 9 kV before charge breakdown.     

Methods of estimation of equilibrium charge distribution of ions in solid and gaseous media

The new version of theoretical estimation of equilibrium charge distribution of ions passing through the matter is proposed. This estimation is based on the correction of charge exchange cross sections for gases taking into account the density effect. The results of calculations are compared with experimental data and with empirical estimation based on the averaging of experimental data for charge distributions of ions in gases and solids. The theoretical method describes the experimental oscillations of width of the charge distribution in contrast to the empirical method.     

Energy loss of heavy ions in carbon foils

The energy loss of Ar, Ti, Kr, Xe, Pb and U ions in the energy range from 0.2 to 1.4 MeV/amu in carbon foils was measured. The results are compared with theoretical and semiempirical estimations.     

Empirical estimation of the equilibrium charge distribution of heavy ions in solid and gaseous media

Based on the analysis of experimental data on equilibrium charge distributions of ions in gases and solid media, the analytical parameterization of the charge distribution width as a function of the average ion charge and nuclear charges of the ion and the target atom and that of the asymmetry as a function of the average ion charge are obtained. The proposed relations are applicable in a broad energy interval and describe the existing experimental data satisfactorily.     

Secondary ion emission from Si bombarded with large Ar cluster ions under UHV conditions

Si was bombarded with size-selected 40 keV Ar cluster ions and positive secondary ions were measured using the time-of-flight technique under high and ultra-high vacuum (HV and UHV respectively) conditions. Si⁺ ions were main species detected under the incidence of 40 keV Ar cluster ions, and the yields of Si cluster ions such as Si₄⁺ were also extremely high under both conditions. On the other hand, oxidized secondary ions such as SiO⁺ were detected with high intensity only under the HV condition. The yield ratios of oxidized ions decreased in UHV to less than 1% of their values in HV. The effect of residual gas pressure on Si cluster ion yields is relatively low compared to oxidized ions, and the UHV condition is required to obtain accurate secondary ion yields.     

Extremely low-energy projectiles for SIMS using size-selected gas cluster ions

A new cluster time-of-flight secondary ion mass spectrometry (TOF-SIMS) was developed using a size-selected gas cluster ion as a projectile. Since a large gas cluster ion can generate many low-energy constituent atoms in a collision with the surface, it causes multiple and ultra low-energy sputtering. The mean kinetic energy of constituent atoms is provided by dividing the acceleration energy of the gas cluster ion by the number of constituent atoms. Therefore, the sputtering can be controlled to minimize the decomposition of sample molecules and substrate material by precisely adjusting the number of constituent atoms (the cluster size) and/or acceleration energy of the gas cluster ion. The cluster size was selected on the basis of the time-of-flight method using two ion deflectors attached along the ion-beam line. A high resolution of 11.7 was achieved for the cluster size/size width (M/ΔM) of Ar-cluster ions.