Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional th...Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory（DFT）based calculations. We found that the Fe atoms were adsorbed on the centers of H2Nc molecules and formed Fe–H2Nc complexes at low coverage. DFT calculations show that Fe sited in the center of the molecule is the most stable configuration, in good agreement with the experimental observations. After an Fe–H2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform size and adsorbed dispersively at the interstitial positions of Fe–H2Nc complex monolayer. Therefore, the H2Nc monolayer grown on Ag（111） could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.展开更多
We prepare a well-defined C84 monolayer on the surface of Ag （111） and study the geometric structure by scanning tunneling microscopy （STM）. The C84 molecules form a nearly close-packed incommensurate R30° la...We prepare a well-defined C84 monolayer on the surface of Ag （111） and study the geometric structure by scanning tunneling microscopy （STM）. The C84 molecules form a nearly close-packed incommensurate R30° lattice. The lattice is long-distance ordered with numerous local disorders. The monolayer exhibits complex bright/dim contrast; the largest height difference between the molecules can be greater than 0.4 nm. Annealing the monolayer at 380 ℃ can desorb part of the molecules, but more than sixty percent molecules stay on the Ag （111） surface even after the sample has been annealed at 650 ℃. Our analyses reveal that the 7-atom pits form beneath many molecules. Some other molecules sit at the 1-atom pits. Ag adatoms （those removed substrate atoms, accompanying the pit formation） play a very important role in this system. The adatoms can either stabilize or destabilize the monolayer, depending on the distribution manner of the adatoms at the interface. The distribution manner is determined by the co-play of the following factors： the dimension of the interstitial regions of the C84 overlayer, the number of the adatoms, and the long-distance migration of part adatoms.展开更多
The adsorption and decomposition of ethylene oxide(EtO)on Cl-modified and oxygen-pre-covered Ag(111)at low temperatures with high resolution electron energy loss spectroscopy(HREELS)arestudied.At 140 K,EtO is molecula...The adsorption and decomposition of ethylene oxide(EtO)on Cl-modified and oxygen-pre-covered Ag(111)at low temperatures with high resolution electron energy loss spectroscopy(HREELS)arestudied.At 140 K,EtO is molecularly adsorbed on the surface.At above 230K.with atomic oxygen on thesurface,a small amount of EtO decomposes into ethylene and is oxidized to produce some oxidation productsas water,etc.while with dioxygen on the surface,a large amount of EtO decomposes into ethylene and isoxidized to produce large amounts of oxidation products like water and so on.The experimental resultsshowed that chlorine can,on the one hand,decrease the adsorption amount of EtO and,on the other hand,inhibit the further oxidation of EtO.展开更多
The formation, structural and electronic properties of silicene oxides（SOs） that result from the oxidation of silicene on Ag（111） surface have been investigated in the framework of density functional theory（DFT）...The formation, structural and electronic properties of silicene oxides（SOs） that result from the oxidation of silicene on Ag（111） surface have been investigated in the framework of density functional theory（DFT）.It is found that the honeycomb lattice of silicene on the Ag（111） surface changes after the oxidation. SOs are strongly hybridized with the Ag（111） surface so that they possess metallic band structures. Charge accumulation between SOs and the Ag（111） surface indicates strong chemical bonding, which dramatically affects the electronic properties of SOs. When SOs are peeled off the Ag（111） surface, however, they may become semiconductors.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61390501,51325204,and 11204361)the National Basic Research Program of China(Grant Nos.2011CB808401 and 2011CB921702)+1 种基金the National Key Scientific Instrument and Equipment Development Project of China(Grant No.2013YQ1203451)the National Supercomputing Center in Tianjin,China,and the Chinese Academy of Sciences
文摘Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory（DFT）based calculations. We found that the Fe atoms were adsorbed on the centers of H2Nc molecules and formed Fe–H2Nc complexes at low coverage. DFT calculations show that Fe sited in the center of the molecule is the most stable configuration, in good agreement with the experimental observations. After an Fe–H2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform size and adsorbed dispersively at the interstitial positions of Fe–H2Nc complex monolayer. Therefore, the H2Nc monolayer grown on Ag（111） could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11079028 and 11374258)
文摘We prepare a well-defined C84 monolayer on the surface of Ag （111） and study the geometric structure by scanning tunneling microscopy （STM）. The C84 molecules form a nearly close-packed incommensurate R30° lattice. The lattice is long-distance ordered with numerous local disorders. The monolayer exhibits complex bright/dim contrast; the largest height difference between the molecules can be greater than 0.4 nm. Annealing the monolayer at 380 ℃ can desorb part of the molecules, but more than sixty percent molecules stay on the Ag （111） surface even after the sample has been annealed at 650 ℃. Our analyses reveal that the 7-atom pits form beneath many molecules. Some other molecules sit at the 1-atom pits. Ag adatoms （those removed substrate atoms, accompanying the pit formation） play a very important role in this system. The adatoms can either stabilize or destabilize the monolayer, depending on the distribution manner of the adatoms at the interface. The distribution manner is determined by the co-play of the following factors： the dimension of the interstitial regions of the C84 overlayer, the number of the adatoms, and the long-distance migration of part adatoms.
文摘The adsorption and decomposition of ethylene oxide(EtO)on Cl-modified and oxygen-pre-covered Ag(111)at low temperatures with high resolution electron energy loss spectroscopy(HREELS)arestudied.At 140 K,EtO is molecularly adsorbed on the surface.At above 230K.with atomic oxygen on thesurface,a small amount of EtO decomposes into ethylene and is oxidized to produce some oxidation productsas water,etc.while with dioxygen on the surface,a large amount of EtO decomposes into ethylene and isoxidized to produce large amounts of oxidation products like water and so on.The experimental resultsshowed that chlorine can,on the one hand,decrease the adsorption amount of EtO and,on the other hand,inhibit the further oxidation of EtO.
基金supported by the National Basic Research Program of China (Grant No. 2013CB632101)the National Natural Science Foundation of China (Grant Nos. 61222404 and 61474097)the Program of the Ministry of Education of China for Innovative Research Teams in Universities (Grant No. IRT13R54)
文摘The formation, structural and electronic properties of silicene oxides（SOs） that result from the oxidation of silicene on Ag（111） surface have been investigated in the framework of density functional theory（DFT）.It is found that the honeycomb lattice of silicene on the Ag（111） surface changes after the oxidation. SOs are strongly hybridized with the Ag（111） surface so that they possess metallic band structures. Charge accumulation between SOs and the Ag（111） surface indicates strong chemical bonding, which dramatically affects the electronic properties of SOs. When SOs are peeled off the Ag（111） surface, however, they may become semiconductors.
