Neutralization ofH−near vicinal metal surfaces
Neutralization ofH−near vicinal metal surfaces
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H−近邻金属表面的中和
DOI：
10.1103/physreva.74.012901
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发表时间：
2006
影响因子：
2.9
通讯作者：
U. Thumm
中科院分区：
文献类型：
--
作者：
B. Obreshkov;U. Thumm
我们计算了H{sup -}离子与金属邻位面碰撞时由于电荷转移而产生的中和几率。我们应用一个统计的梯度修正的动能和局部密度近似的交换相关能的M-Fermi模型来计算表面的基态电子结构。在与平面计算相比，我们发现功函数的变化，诱导的邻位超结构，在良好的协议与发表的实验和理论数据。我们评估的位移和宽度的H{sup -}亲和能级共振的离子附近的表面的固定位置。对于入射阴离子的动能为1千电子伏，计算出的离子中和概率敏感地依赖于影响方向，点的最接近的轨迹，和表面形态。我们发现，如果H{sup -}离子从上方接近台阶，则离子存活的可能性更大，与在其他相同的散射条件下从下方接近台阶的离子相比。特别是，在单原子阶梯Al表面的平台处反射后的电子损失被预测为共振增强，如果离子从下面接近一个步骤。
We calculate the neutralization probability of H{sup -} ions due to charge transfer in collisions with metal vicinal surfaces. We apply a statistical Thomas-Fermi model with gradient correction to the kinetic energy and a local density approximation for the exchange-correlation energy to compute the ground-state electronic structure of the surface. In comparison with calculations for flat surfaces, we find work-function changes, induced by the vicinal superstructure, in good agreement with published experimental and theoretical data. We evaluate the shift and width of the H{sup -} affinity level resonance for fixed positions of the ion near the surface. For incident anions with a kinetic energy of 1 keV, the calculated ion-neutralization probabilities depend sensitively on the impact direction, point of closest approach of the trajectory, and the surface morphology. We find that the ion survival is more likely if the H{sup -} ions approach the step from above, as compared to ions that approach a step from below under otherwise identical scattering conditions. In particular, the electron loss after reflection at a terrace of a monoatomically stepped Al surface is predicted to be resonantly enhanced if the ion approaches a step from below.