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- Creator:
- Huan, Qing, Cheng, Zhihai, Gao, Li, Zhang, Lizhi, Jiang, Nan, Liu, Qi, Guo, Haiming, Lin, Xiao, Du, Shi-Xuan, Deng, Zhitao, He, Xiao-Bo, and Gao, Hong-jun
- Description:
- Adsorption behavior of iron-phthalocyanine (FePc) at low submonolayer coverage on a reconstructed Au(111) single crystalline surface was investigated by a combination of low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. A site- and orientation-selective adsorption was found at different temperatures and molecular coverages by means of STM. Further DFT calculations demonstrate that the energy difference between different adsorption configurations leads to the selectivity, and thus the formation of one-dimensional molecular chains on the monatomic step edges in the fcc surface reconstruction domains. The exact adsorption site and configuration of the FePc molecule as well as the simulated STM images are obtained on the basis of DFT calculations, which is in good agreement with experimental observations.
- Resource Type:
- Article
- Identifier:
- 1932-7447
- Campus Tesim:
- Northridge
- Creator:
- Cheng, Zhihai, Gao, Li, Shi, Dong-Xia, Jiang, Nan, Liu, Qi, Guo, Haiming, Du, Shi-Xuan, Gao, Hong-jun, and Deng, Zhitao
- Description:
- Adsorption behavior of iron(II) phthalocyanine (FePc) on Au(111) surface at submonolayer coverage has been investigated using low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. At the initial adsorption stage, FePc molecules prefer to adsorb on terrace dispersedly as isolated adsorbates because of the stronger molecule?substrate interaction than the lateral intermolecular interaction. Two different configurations of FePc on Au(111) surface are resolved on the basis of STM image analysis and are further identified by DFT calculations. When increasing molecule coverage, the intermolecular interaction becomes more important. The FePc molecules assemble to dimers, trimers, and short chains and even peculiar porous hexamers with two configurations. At a saturated coverage, highly ordered FePc monolayer with only one configuration of FePc is observed. The results indicate that the adsorption behavior of FePc on Au(111) is governed by a coverage-dependent competition between molecule?substrate and intermolecular interactions.
- Resource Type:
- Article
- Identifier:
- 1932-7447
- Campus Tesim:
- Northridge
- Creator:
- Gray, Glen L., Chiu, Victoria, Li, Pei, and Liu, Qi
- Description:
- Accounting information systems (AIS) is the intersection of the accounting domains and the computer science and information systems domains. Periodically, new technology emerges that generates a new AIS research to explore the application of that technology to the accounting domains. AIS researchers compete with researchers in information systems, computer science, electrical engineering, plus other technology-related disciplines. AIS researchers are also frequently competing with the organizations (e.g., accounting firms) that have resources that far exceed academic resources. This paper explores the life cycle of expert systems research by accounting researchers to provide general insights into the roles of accounting researchers in technology domains. From 1980 through 2011, 233 accounting-related expert systems papers were published. Those publications generally transitioned through the industry life cycle stages. The peak years were the early 1990s. Although most of the expert system publications appeared in AIS-oriented publications, by the 2005-2011 timeframe, a little more than 50% appeared in non-system journals. There were 352 unique authors involved in writing the 233 articles. Interestingly, 14 (4%) authors wrote 30% of the papers and 303 (86%) authors wrote just one paper. In the practice community, Brown (1991) listed 43 expert systems in use or under development at the Big 6, all of which have disappeared.
- Resource Type:
- Article
- Identifier:
- http://jebcl.com/symposium/wp-content/uploads/2013/08/Expert-Systems-Life-Cycle.pdf, 1873-4723
- Campus Tesim:
- Northridge
- Creator:
- Cheng, Zhihai, Lin, Xiao, Ji, Wei, Xie, X.C., Hofer, Werner A., Deng, Zhitao, Guo, Wei, Gao, Li, Liu, Qi, Hu, Y.B., Jiang, Nan, Du, Shi-Xuan, and Gao, Hong-jun
- Description:
- Kondo resonances are a very precise measure of spin-polarized transport through magnetic impurities. However, the Kondo temperature, indicating the thermal range of stability of the magnetic properties, is very low. By contrast, we find for iron phthalocyanine a Kondo temperature in spectroscopic measurements which is well above room temperature. It is also shown that the signal of the resonance depends strongly on the adsorption site of the molecule on a gold surface. Experimental data are verified by extensive numerical simulations, which establish that the coupling between iron states and states of the substrate depends strongly on the adsorption configuration.
- Resource Type:
- Article
- Identifier:
- 0031-9007
- Campus Tesim:
- Northridge
- Creator:
- Cheng, Zhihai, Du, Shi-Xuan, He, Xiao-Bo, Gao, Hung-Jun, Deng, Zhitao, Gao, Li, Liu, Qi, and Lin, Xiao
- Description:
- Growth behavior of iron(II) phthalocyanine (FePc) molecules on Au(111) surface at the initial stage is studied with low-temperature scanning tunneling microscopy. The FePc molecules are separately adsorbed on the face-centered cubic and the hexagonal close-packed regions at the submonolayer regime, indicating that the molecular adsorption is greatly affected by the molecule?substrate interaction. At the monolayer regime, the molecules can form a close-packed ordered structure. When the FePc goes further to the second layer, the unit cell of the formed molecular superstructure shifts compared with the unit cell of the first layer. Comparison of the growth behavior between the FePc and the CoPc also is made to understand the growth difference within the family of the phthalocyanine (Pc) molecules. And it is found that the central metal atom of the metal Pc makes a main contribution to the shift. Our results are helpful for understanding the growth of the Pc molecule family and controlling the related physical properties.
- Resource Type:
- Article
- Identifier:
- 1932-7447
- Campus Tesim:
- Northridge
- Creator:
- Grein, Chistoph H., Zhang, Y.Y., Du, Shi-Xuan, Gao, Hong-jun, Zhang, H.G., Gao, Li, Chang, Yong, Liu, Qi, Kioussis, Nicholas G., Ciani, Anthony, Tari, Suleyman, Jiang, Nan, Li, Jin, and Aqariden, F.
- Description:
- We report for the first time a new methodology to determine molecular configurations of a large molecular complex in a dynamical process on a metal surface by combining time-resolved tunneling spectroscopy (I−t) and density functional theory calculation (DFT). Two examples, (t−Bu)4−ZnPc and FePc, representing molecular rotation and lateral diffusion on Au(111) surfaces, respectively, were applied to demonstrate our method. Through analysis of statistical occupation time for each configuration, the molecular configuration numbers and energy differences between different configurations of these molecular systems could be unambiguously determined. These experimental results are further compared with DFT calculation to determine corresponding molecular configurations. Importantly, through the spatial I−t mapping, valuable insights of molecular surface diffusion paths are obtained.
- Resource Type:
- Article
- Identifier:
- 0031-9007
- Campus Tesim:
- Northridge
- Creator:
- Cheng, Zhihai, Zhang, Y.Y., Du, Shi-Xuan, Hofer, Werner A., Niang, N., Qiu, W.F., Gao, Hong-jun, Zhang, H.G., Gao, Li, Liu, Qi, and Liu, Y.Q.
- Description:
- Experiments and first-principles calculations reveal that we introduce gold adatoms at the surface as the stable contact of the molecule to the surface. An off-center rotation axis is formed by a chemical bonding between a nitrogen atom of the molecule and a gold adatom at the surface, which gives them a well-defined contact while the molecules can have rotation-favorable configurations. Furthermore, these single-molecule rotors self-assemble into large scale ordered arrays on Au(111) surfaces. A fixed rotation axis off center is an important step towards the eventual fabrication of molecular motors or generators.
- Resource Type:
- Article
- Identifier:
- 0031-9007
- Campus Tesim:
- Northridge