In this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Kb, Cs; F, Cl, Br, I), where the position of X changes along 5 typical symmetry directions. For the calculation of quantum chemistry we us...In this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Kb, Cs; F, Cl, Br, I), where the position of X changes along 5 typical symmetry directions. For the calculation of quantum chemistry we use EHMO/ASED method, for the calculation of molecular mechanics we use Buckingham potential (exp-6-1) function, and for the calculation of thermo-chemical cycle we use individually isolating the processes such as the structure variation, charge transfer and charge distribution, and their interactions etc. The calculation results show that (1) In the region of radius r≈0.2 nm of the Ceo cage, the potential field is nearly spherical; (2) Except for Li and Na, the systems are the most stable with minimum energies at the center of C60 cage. For Li and Na, the systems are the most stable with minimum energies at r≈0.16 nm and r≈0.13 nm, respectively. In view of the interactive region of chemical bonds, the interactions between X and the C60 cage do not belong to the classical chemical bonds; (3) The non-bonding interaction between the X and C60 cage are not purely electro-static, in which the electro-static interactions only occupy -90% at most on an average. The repulsion owing to the overlap of the electron cloud and the attraction owing to the dispersion can not be neglected. These two interactions determine the variations of size and trend of the system energies with r; (4) The polarization due to the position of X deviating from the center of C60 cage plays an important role at the most stable positions of Li and Na.展开更多
The structural and electronic properties of N-doped zigzag graphene nanoribbons （N-ZGNRs） adsorbed on Si（001） substrates are investigated with first-principles density functional cMculations. Compared with the fre...The structural and electronic properties of N-doped zigzag graphene nanoribbons （N-ZGNRs） adsorbed on Si（001） substrates are investigated with first-principles density functional cMculations. Compared with the free-standing N-ZGNRs, the energy difference between the substitutional doping at the edge and the inner sites is significantly decreased on the Si substrate. The distribution of the extra charge induced by the N substitutional .dopant keeps the Friedel oscillation feature, and is a main effect that influences the C-Si bonding strength. When N is doped in regions with high C-Si bond densities, the strain induced by the dopant also plays an important role in determining the C-Si bonding interactions. Similar to the undoped case, the strong N-ZGNR/Si interaction destroys the antiferromagnetic coupling of the edge states in N-ZGNR, leading to a non-magnetic ground state for the N-ZGNR/Si heterostructures.展开更多
In situ opticaJ eAnssion spectra for an electron assisted hot filament diamond growth process were successfully measured with spatial resolution of better than 1 mm.The ethession lines from atoAnc hydrogen, molecular ...In situ opticaJ eAnssion spectra for an electron assisted hot filament diamond growth process were successfully measured with spatial resolution of better than 1 mm.The ethession lines from atoAnc hydrogen, molecular hydrogen, CH and CH+ radicals were observed in the visible region. Effects of the substrate bias on ethession spectra and diamond nucleation were also investigated. It is found that substratboan enhance the nucleation density, which may due to the changes of atoAnc hydrogen concentration and the increase of electron mean temperatuxe.展开更多
We obtain the isomer spectra of C30 and C31 dusters by time-going-backward quasi-dynamics method and perform molecular dynamics simulations of the duster growth from isolated atoms in He buffer gas at 2500 K. The geom...We obtain the isomer spectra of C30 and C31 dusters by time-going-backward quasi-dynamics method and perform molecular dynamics simulations of the duster growth from isolated atoms in He buffer gas at 2500 K. The geometrical structures of the isomers of C30 and C31 can be classified into closed cages, open cages, bowls, sheets and other irregular shapes, where closed cages are found to have the lowest potential energies. However, dynamics simulations show that the sheet structures of C30 and C31 are the dominant outcome at the simulation temperature. Compared with relevant experimental results, we propose a different view in interpreting the experimental data and a research procedure to predict isomers that would be formed most probably under specific experimental conditions.展开更多
We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electr...We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electrode is relatively thick, the device of the cross-point Al electrode shows a three-level memory effect, and the counterpart device of the cross-bar Al electrode exhibits a volatile static random access memory effect. When the thickness of the AI electrode is thinner, the above devices demonstrate a flash memory effect. The different memory behaviors of ITO/GO/AI diodes are ascribed to the mode and degree of reduction and oxidation of GO.展开更多
An important precursor 4,5-didodecylthiolph- thalonitrile (DCP) for synthesis of phthalocyanines (Pcs) and subphthalocyanines (SubPcs) was synthesized and the as-sembling structure of this molecule on the basal plane ...An important precursor 4,5-didodecylthiolph- thalonitrile (DCP) for synthesis of phthalocyanines (Pcs) and subphthalocyanines (SubPcs) was synthesized and the as-sembling structure of this molecule on the basal plane of highly oriented pyrolytic graphite (HOPG) surface was characterized using the scanning tunneling microscopy (STM) in ambient conditions. In high-resolution images of the molecules, we found that the arrangement of the cyano groups forms a head-to-head configuration to keep the stability of the entire system. The mismatch of the DCP molecules with the substrate lattice has also been observed in the experiment.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘In this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Kb, Cs; F, Cl, Br, I), where the position of X changes along 5 typical symmetry directions. For the calculation of quantum chemistry we use EHMO/ASED method, for the calculation of molecular mechanics we use Buckingham potential (exp-6-1) function, and for the calculation of thermo-chemical cycle we use individually isolating the processes such as the structure variation, charge transfer and charge distribution, and their interactions etc. The calculation results show that (1) In the region of radius r≈0.2 nm of the Ceo cage, the potential field is nearly spherical; (2) Except for Li and Na, the systems are the most stable with minimum energies at the center of C60 cage. For Li and Na, the systems are the most stable with minimum energies at r≈0.16 nm and r≈0.13 nm, respectively. In view of the interactive region of chemical bonds, the interactions between X and the C60 cage do not belong to the classical chemical bonds; (3) The non-bonding interaction between the X and C60 cage are not purely electro-static, in which the electro-static interactions only occupy -90% at most on an average. The repulsion owing to the overlap of the electron cloud and the attraction owing to the dispersion can not be neglected. These two interactions determine the variations of size and trend of the system energies with r; (4) The polarization due to the position of X deviating from the center of C60 cage plays an important role at the most stable positions of Li and Na.
基金Supported by the National Natural Science Foundation of China under Grant No 11204296the National Basic Research Program of China under Grant No 2013CB933304
文摘The structural and electronic properties of N-doped zigzag graphene nanoribbons （N-ZGNRs） adsorbed on Si（001） substrates are investigated with first-principles density functional cMculations. Compared with the free-standing N-ZGNRs, the energy difference between the substitutional doping at the edge and the inner sites is significantly decreased on the Si substrate. The distribution of the extra charge induced by the N substitutional .dopant keeps the Friedel oscillation feature, and is a main effect that influences the C-Si bonding strength. When N is doped in regions with high C-Si bond densities, the strain induced by the dopant also plays an important role in determining the C-Si bonding interactions. Similar to the undoped case, the strong N-ZGNR/Si interaction destroys the antiferromagnetic coupling of the edge states in N-ZGNR, leading to a non-magnetic ground state for the N-ZGNR/Si heterostructures.
文摘In situ opticaJ eAnssion spectra for an electron assisted hot filament diamond growth process were successfully measured with spatial resolution of better than 1 mm.The ethession lines from atoAnc hydrogen, molecular hydrogen, CH and CH+ radicals were observed in the visible region. Effects of the substrate bias on ethession spectra and diamond nucleation were also investigated. It is found that substratboan enhance the nucleation density, which may due to the changes of atoAnc hydrogen concentration and the increase of electron mean temperatuxe.
基金Supported by the National Natural Science Foundation of China under Grant No 10574030.
文摘We obtain the isomer spectra of C30 and C31 dusters by time-going-backward quasi-dynamics method and perform molecular dynamics simulations of the duster growth from isolated atoms in He buffer gas at 2500 K. The geometrical structures of the isomers of C30 and C31 can be classified into closed cages, open cages, bowls, sheets and other irregular shapes, where closed cages are found to have the lowest potential energies. However, dynamics simulations show that the sheet structures of C30 and C31 are the dominant outcome at the simulation temperature. Compared with relevant experimental results, we propose a different view in interpreting the experimental data and a research procedure to predict isomers that would be formed most probably under specific experimental conditions.
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB723402 and 2014CB648300the National Natural Science Foundation of China under Grant Nos 61204095 and 61475074+3 种基金the National Science Fund for Excellent Young Scholars under Grant No 21322402the Natural Science Foundation of Jiangsu Province under Grant No BK2012431,the Natural Science Foundation of the Education Committee of Jiangsu Province under Grant No 14KJB510027the Ministry of Education of China under Grant No IRT1148the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electrode is relatively thick, the device of the cross-point Al electrode shows a three-level memory effect, and the counterpart device of the cross-bar Al electrode exhibits a volatile static random access memory effect. When the thickness of the AI electrode is thinner, the above devices demonstrate a flash memory effect. The different memory behaviors of ITO/GO/AI diodes are ascribed to the mode and degree of reduction and oxidation of GO.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.20073053 and 20103008)the Foundation of the Chinese Academy of Sciences.
文摘An important precursor 4,5-didodecylthiolph- thalonitrile (DCP) for synthesis of phthalocyanines (Pcs) and subphthalocyanines (SubPcs) was synthesized and the as-sembling structure of this molecule on the basal plane of highly oriented pyrolytic graphite (HOPG) surface was characterized using the scanning tunneling microscopy (STM) in ambient conditions. In high-resolution images of the molecules, we found that the arrangement of the cyano groups forms a head-to-head configuration to keep the stability of the entire system. The mismatch of the DCP molecules with the substrate lattice has also been observed in the experiment.
