Electron-hole pair excitation determines the mechanism of hydrogen atom adsorption
Electron-hole pair excitation determines the mechanism of hydrogen atom adsorption
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DOI：
10.1126/science.aad4972
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发表时间：
2015-12-11
期刊：
影响因子：
56.9
通讯作者：
Wodtke, Alec M.
中科院分区：
文献类型：
--
作者：
Buenermann, Oliver;Jiang, Hongyan;Wodtke, Alec M.
原子和分子在表面碰撞中失去多少平动能决定了它们是吸附还是散射。氢原子附着在金属表面的事实提出了一个基本问题。动量和能量守恒要求在二元碰撞中，轻H原子不能有效地将其能量传递给固体中较重的原子。那么氢原子是如何有效地附着在金属表面的呢？我们通过实验证明，在绝缘表面（金单晶表面上吸附的氙层）上的h原子碰撞确实几乎是弹性的，遵循能量和动量守恒的预测。相比之下，h原子与裸金表面的碰撞表现出巨大的平动能量损失，这可以通过描述电子-空穴对激发的原子级模拟来重现。
How much translational energy atoms and molecules lose in collisions at surfaces determines whether they adsorb or scatter. The fact that hydrogen (H) atoms stick to metal surfaces poses a basic question. Momentum and energy conservation demands that the light H atom cannot efficiently transfer its energy to the heavier atoms of the solid in a binary collision. How then do H atoms efficiently stick to metal surfaces? We show through experiments that H-atom collisions at an insulating surface (an adsorbed xenon layer on a gold single-crystal surface) are indeed nearly elastic, following the predictions of energy and momentum conservation. In contrast, H-atom collisions with the bare gold surface exhibit a large loss of translational energy that can be reproduced by an atomic-level simulation describing electron-hole pair excitation.