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Negative ion formation by neutral hydrogen atom grazing scattering from a LiF(100) surface
RSC Advances ( IF 3.9 ) Pub Date : 2021-1-22 , DOI: 10.1039/d0ra08486g Bo Jin 1 , Hu Zhou 1, 2 , Zewen Zong 1 , Xin Zhang 1 , Guangyi Wang 3 , Lihua Zhou 1 , Ximeng Chen 1
RSC Advances ( IF 3.9 ) Pub Date : 2021-1-22 , DOI: 10.1039/d0ra08486g Bo Jin 1 , Hu Zhou 1, 2 , Zewen Zong 1 , Xin Zhang 1 , Guangyi Wang 3 , Lihua Zhou 1 , Ximeng Chen 1
Affiliation
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We present a theoretical description of negative ion conversion of the grazing scattering of neutral hydrogen atoms on LiF(100) surface. Here, in addition to the capture of a valence band electron near a surface F− site by an incident H atom, the Coulomb repulsive barrier tunneling behavior is also considered to treat the detachment of the affinity electron from the formed H− ion to vacuum through its interaction with the surface F− site. With incorporation of the image-attraction-induced increase on the vertical component of the projectile energy and the collective dielectric screening effect of surrounding anions and cations on the charge of surface F− site which participates in the electron detachment, the image attractive interaction was revealed to obviously increase the electron detachment probability, in turn obviously decreasing the final negative ion yield. Moreover, the sub-eV order of the energy defect between the H− affinity level and the unoccupied image state induced by the potential field of the H− image charge in LiF leads to an additional H− destruction channel in which H− affinity electron transfers to the unoccupied image state without electron emission by a nearly resonant charge transfer manner. A clear picture of this electron loss process is also presented. Our present results well reproduce the experimental observation in the whole velocity range and the high fraction of H− ion yield as an alternative solution can be used on the implantation of ITER device.
中文翻译：
中性氢原子从 LiF(100) 表面掠散射形成负离子
我们提出了 LiF(100) 表面上中性氢原子掠散射的负离子转换的理论描述。这里，除了通过入射H原子捕获表面F -位点附近的价带电子外，库仑排斥势垒隧穿行为也被认为是处理亲和电子从形成的H -离子脱离到真空通过它与表面 F -位点的相互作用。结合图像吸引力引起的弹丸能量垂直分量的增加以及周围阴离子和阳离子对表面 F 电荷的集体介电屏蔽效应-位点参与电子脱离，图像吸引力相互作用显着增加电子脱离概率，进而显着降低最终负离子产率。此外，H -亲和能级与 LiF 中 H -图像电荷的势场引起的未占据图像状态之间的能量缺陷的亚 eV级导致额外的 H -破坏通道，其中 H -亲和电子通过近共振电荷转移方式转移到无电子发射的未占据像态。还提供了这种电子损失过程的清晰图片。我们目前的结果很好地再现了整个速度范围内的实验观察结果，并且高比例的 H -离子产率作为替代解决方案可用于 ITER 装置的注入。
更新日期：2021-01-22
中文翻译：
中性氢原子从 LiF(100) 表面掠散射形成负离子
我们提出了 LiF(100) 表面上中性氢原子掠散射的负离子转换的理论描述。这里，除了通过入射H原子捕获表面F -位点附近的价带电子外，库仑排斥势垒隧穿行为也被认为是处理亲和电子从形成的H -离子脱离到真空通过它与表面 F -位点的相互作用。结合图像吸引力引起的弹丸能量垂直分量的增加以及周围阴离子和阳离子对表面 F 电荷的集体介电屏蔽效应-位点参与电子脱离，图像吸引力相互作用显着增加电子脱离概率，进而显着降低最终负离子产率。此外，H -亲和能级与 LiF 中 H -图像电荷的势场引起的未占据图像状态之间的能量缺陷的亚 eV级导致额外的 H -破坏通道，其中 H -亲和电子通过近共振电荷转移方式转移到无电子发射的未占据像态。还提供了这种电子损失过程的清晰图片。我们目前的结果很好地再现了整个速度范围内的实验观察结果，并且高比例的 H -离子产率作为替代解决方案可用于 ITER 装置的注入。
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