This paper computationally investigates the RhSin （n = 1 6） clusters by using a density functional approach. Geometry optimizations of the RhSin （n = 1 6） clusters are carried out at the B3LYP level employing LanL...This paper computationally investigates the RhSin （n = 1 6） clusters by using a density functional approach. Geometry optimizations of the RhSin （n = 1 6） clusters are carried out at the B3LYP level employing LanL2DZ basis sets. It presents and discusses the equilibrium geometries of the RhSin （n = 1-6） clusters as well as the corresponding averaged binding energies, fragmentation energies, natural populations, magnetic properties, and the energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Theoretical results show that the most stable RhSin（n = 1-6） isomers keep an analogous framework of the corresponding Sin＋1 clusters, the RhSi3 is the most stable cluster in RhSin （n = 1-6） isomers. Furthermore, the charges of the lowest-energy RhSin （n = 1-6） clusters transfer mainly from Si atom to Rh atom. Meanwhile, the magnetic moments of the RhSin（n = 1-6） arises from the 4d orbits of Rh atom. Finally, compared with the Sin＋1 cluster, the chemical stability RhSin clusters are universally improved.展开更多
The green-emitting fluorescent powders of nano Y2O3：Er^3＋ were fabricated by the coprecipitation method. The X-ray diffrac- tion pattern shows that as-prepared Y2O3：Er^3＋ is the cubic phase crystal with a grain si...The green-emitting fluorescent powders of nano Y2O3：Er^3＋ were fabricated by the coprecipitation method. The X-ray diffrac- tion pattern shows that as-prepared Y2O3：Er^3＋ is the cubic phase crystal with a grain size of about 30 nm. The UV-Vis spec- trum indicates Y^O3：Er^3＋ exhibits five ultraviolet visible absorption peaks at 365, 377, 489, 521 and 652 nm respectively. Meanwhile, the fluorescence spectra of Y2O3：Er^3＋ display four emission peaks at 522, 537, 550 and 562 nm at the excitation of 365,377 and 521 nm, respectively. The green-emitting fluorescent mechanism of Y2O3：Er^3＋ is proposed as well. Additionally, the temperature dependence of fluorescence properties and metal Ag fluorescence enhancement effect are investigated. Results show that increasing the annealing temperature and metal Ag doping both can enhance the fluorescence intensity. The maxi- mum enhancement is 87.5% after Ag is doped.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10247007)the Natural Science Foundation of Shaanxi Province (Grant No 2002A09)the Special Item Foundation of Educational Committee of Shaanxi Province (Grant No 02JK050)
文摘This paper computationally investigates the RhSin （n = 1 6） clusters by using a density functional approach. Geometry optimizations of the RhSin （n = 1 6） clusters are carried out at the B3LYP level employing LanL2DZ basis sets. It presents and discusses the equilibrium geometries of the RhSin （n = 1-6） clusters as well as the corresponding averaged binding energies, fragmentation energies, natural populations, magnetic properties, and the energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Theoretical results show that the most stable RhSin（n = 1-6） isomers keep an analogous framework of the corresponding Sin＋1 clusters, the RhSi3 is the most stable cluster in RhSin （n = 1-6） isomers. Furthermore, the charges of the lowest-energy RhSin （n = 1-6） clusters transfer mainly from Si atom to Rh atom. Meanwhile, the magnetic moments of the RhSin（n = 1-6） arises from the 4d orbits of Rh atom. Finally, compared with the Sin＋1 cluster, the chemical stability RhSin clusters are universally improved.
基金supported by the National Natural Science Foundation of China (Grant No. 21176199)the Research Fund for the Doctoral Program of Higher Education (Grant No. 20096101110013)+2 种基金the Industrialization Cultivation Item of Shaanxi Province Educational Department(Grant No. 2011JG05)the Natural Science Foundation of Shaanxi Province (Grant No. 2011JM1001)the Education and Teaching Reform Project of Northwest University (Grant No. Fjg10004)
文摘The green-emitting fluorescent powders of nano Y2O3：Er^3＋ were fabricated by the coprecipitation method. The X-ray diffrac- tion pattern shows that as-prepared Y2O3：Er^3＋ is the cubic phase crystal with a grain size of about 30 nm. The UV-Vis spec- trum indicates Y^O3：Er^3＋ exhibits five ultraviolet visible absorption peaks at 365, 377, 489, 521 and 652 nm respectively. Meanwhile, the fluorescence spectra of Y2O3：Er^3＋ display four emission peaks at 522, 537, 550 and 562 nm at the excitation of 365,377 and 521 nm, respectively. The green-emitting fluorescent mechanism of Y2O3：Er^3＋ is proposed as well. Additionally, the temperature dependence of fluorescence properties and metal Ag fluorescence enhancement effect are investigated. Results show that increasing the annealing temperature and metal Ag doping both can enhance the fluorescence intensity. The maxi- mum enhancement is 87.5% after Ag is doped.
