Canário Ana Rita, Esaulov Vladimir A
Laboratoire des Collisions Atomiques et Moléculaires (Unité Mixte CNRS Université UMR8625), Université Paris Sud, 91405 Orsay, France.
J Chem Phys. 2006 Jun 14;124(22):224710. doi: 10.1063/1.2205849.
The results of a detailed study of Li(+) neutralization in scattering on Ag and Au clusters and thin films supported on TiO(2) are presented. A very efficient neutralization is observed on small clusters with a decrease for the smallest clusters. These results closely follow the size-effects observed in the reactivity of these systems. The energy dependence of the neutralization was studied for the larger clusters (>4 nm) and observed to be similar in trend to the one observed on films and bulk (111) crystals. A general discussion of possible reasons of the enhancement in neutralization is presented and these changes are then tentatively discussed in terms of progressive modifications in the electronic structure of clusters as a function of reduction in size and as it evolves from metallic-like to discretised states. The highest neutralization efficiency would appear to correspond to clusters sizes for which a metal to nonmetal transition occurs. The relative position of the Li level and the highest occupied molecular orbital in the molecular cluster can be expected to strongly affect the electron transfer processes, which in this case should be described in a molecular framework.
本文展示了对Li(+)在Ag和Au团簇以及负载于TiO(2)上的薄膜散射过程中中和作用的详细研究结果。在小团簇上观察到非常高效的中和作用，而最小的团簇中和作用有所降低。这些结果与在这些体系反应性中观察到的尺寸效应密切相关。针对较大团簇（>4 nm）研究了中和作用的能量依赖性，发现其趋势与在薄膜和块状（111）晶体上观察到的相似。本文对中和作用增强的可能原因进行了一般性讨论，然后根据团簇电子结构随尺寸减小以及从类金属态向离散态演变过程中的逐步变化，对这些变化进行了初步探讨。最高的中和效率似乎对应于发生金属到非金属转变的团簇尺寸。分子团簇中Li能级与最高占据分子轨道的相对位置预计会强烈影响电子转移过程，在这种情况下，应在分子框架内对其进行描述。
