Charge-state equilibration length of a highly charged ion inside a carbon solid.
Charge-state equilibration length of a highly charged ion inside a carbon solid.
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DOI：
10.1103/physreva.50.1435
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发表时间：
1994-08
期刊：
影响因子：
--
通讯作者：
Herrmann;Cocke;Ullrich;Hagmann;Stoeckli;Schmidt-Boecking
中科院分区：
文献类型：
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作者：
Herrmann;Cocke;Ullrich;Hagmann;Stoeckli;Schmidt-Boecking
研究了初始电荷态为{\mathit{q}}_{\mathit{i}}$=8，12，16的576 keV{\mathm{Ar}^{\mathit{q}+}$离子穿透310\aA}厚度的碳箔的情况。测量了弹丸的能量损失和最终电荷态分布。在几个百分点的分辨率内，没有发现这些数据对弹丸初始电荷状态的依赖。此外，还测量了弹丸在箔片前后发射的俄歇电子的相对产额。根据这些产额，我们可以推导出Ar离子在箔内迅速达到平衡激发态，它不依赖于初始电荷状态${\mathit{q}}_{\mathit{i}}$。根据测量的能量损失数据，我们得到了射弹在大约一个碳层的箔内的平均荷态平衡长度的上限。这一结果意味着弹丸和固体之间的电子转移机制具有极大的横截面。用经典的超势垒模型估算这个截面，很难解释观察到的离子和固体之间非常大的电荷交换截面。
The penetration of 576-keV ${\mathrm{Ar}}^{\mathit{q}+}$ ions with initial charge states ${\mathit{q}}_{\mathit{i}}$=8,12,16 through a carbon foil of 310 \AA{} thickness has been investigated. The projectile's energy loss and final charge-state distribution have been measured. Within a resolution of a few percent no dependence of these data on the projectile's initial charge state was found. Furthermore the relative yield of Auger electrons emitted by the projectile before and after the foil was detected. From these yields we could derive that the Ar ions quickly reach an equilibrium excitation state inside the foil that does not depend on the initial charge state ${\mathit{q}}_{\mathit{i}}$. From the measured energy-loss data we derive an upper limit for the projectile's average charge-state equilibration length ${\mathit{x}}_{\mathit{e}}$ inside the foil of approximately one carbon layer. This result implies extremely large cross sections for electron transfer mechanisms between projectile and solid. An estimation of this cross section by using the classical over-barrier model hardly explains the observed, very large charge-exchange cross sections between ion and solid.