Two-dimensional sub-nano mapping of surface photochemistry

本论文主要利用扫描隧道显微镜和其它表面科学技术研究了Ag（110）上AgO一维表面化合物的光化学和热化学。主要结果如下：1. AgO在Ag（110）表面上光致氧消除反应的反应位点我们阐明了AgO链上的氧在Ag（110）表面上的光致氧消除反应的反应位点。该反应是由AgO链的电子激发引发的，并且在碳化物碳存在的位置处发生CO形成。在该表面上，AgO链通过位点上氧的光消除而断裂。2.碳化物碳对AgO链结构的影响：碳化物碳钉扎AgO链，使链不表现出任何结构波动，并且观察到链的配对在低覆盖度下。另一方面，在低覆盖度下，链在干净的表面上伸展，并表现出广泛的结构波动。3.热氧消除的反应位点及结构波动与反应活性的相关性：我们发现，在低温下，热氧消除发生在链的末端，在那里链的一维结构保持不变。然而，在室温下，当一维链开始波动时，反应增强。这表明结构波动在链中产生扭结，并且扭结处的氧原子被消除。因此，反应位点是动态产生的。

We have investigated mainly the following subject on photo-and thermo chemistry of one dimensional surface compound of AgO on Ag(110) by scanning tunneling microscope and the other surface science techniques. Here is a summary of main results :1.Reaction sites of photo-induced oxygen elimination reaction of AgO on Ag(110).We clarified the reaction sited of uv-light induced-photoelimination reaction of oxygen from AgO chains on a Ag(110) surface. The reaction is initiated with electronic excitation of AgO chains and CO formation takes place at the site where carbidic carbon exists. On this surface, AgO chains are fragmented by the photo-elimination of oxygen at the sites.2.Effect of carbidic carbon on the structure of AgO chains :Carbidic carbon pins AgO chains so that the chains do not show any structural fluctuations and the pairing of chains is observed at the low coverage. On the other hand, chains spread on a clean surface at the low coverage and shows extensive structural fluctuations.3.Reaction sites of thermal oxygen elimination and correlation between structural fluctuation and reactivity :We found that thermal oxygen elimination takes place at the ends of chains at low temperature where the one-dimensional structure of chains is hold. However, at room temperature, the reaction is enhanced when one-dimensional chains start fluctuating. This indicates that the structural fluctuation creates kinks in the chain, and oxygen atoms at the kinks are eliminated. Thus, the reaction sites are created dynamically.