【摘要】 采用反冲离子飞行时间-散射离子位置灵敏符合测量技术,测量了能量范围在0.7v0—4.4v0(v0为玻尔速度)的碳离子Cq+(q=1—4)与He原子碰撞过程不同出射道靶原子的双电离与单电离截面比R,包括入射离子不损失电子(直接电离)的出射道(Rq,q),入射离子俘获一个电子的出射道(Rq,q-1)和入射离子损失一个电子的出射道(Rq,q+1),并研究了R随入射C离子的能量及电荷态的变化关系.实验表明,对给定电荷态的入射离子,靶原子的双电离与单电离截面比R与出射道有很强的依赖关系,即Rq,q<Rq,q+1<Rq,q-1.直接电离出射道截面比Rq,q与入射离子电荷态几乎无关,而入射离子俘获一个电子的出射道和损失一个电子的出射道靶原子双电离与单电离截面比Rq,q-1和Rq,q+1却与入射离子电荷态有很强的关系.采用原子极化理论和电子屏蔽与反屏蔽作用对实验结果进行了解释.更多还原

【Abstract】 The cross-section ratios for the double-to-single ionization of He associated with no projectile charge change(R-q,q),single-electron capture(R-q,q-1)and single-electron loss(R-q,q+1)were measured using coincidence technique.The coincidences resulted from the signals of recoil ions and scattered projectiles.For a given incoming projectile charge state the double-to-single ionization ratios vary strongly with the outgoing reaction channel.It is found that R-q,q<R-q,q+1<R-q,q-1.For direct ionization,R-q,q is nearly independent of the incident projectile charge state.However,for ionization associated with single-electron capture and single-electron loss by the projectile,R-q,q-1 and R-q,q+1 depend strongly on the incident charge state of the projectile.These ionization ratios are interpreted in terms of theories of the atomic polarization effect and the screening and antiscreening effect of the electrons around the core.更多还原