A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copp...A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copper clusters. Our results show that the three-dimensional isomers of copper clusters start from Cu7 cluster and then show a tendency to form more compact structures. The results of the formation energy and the second derivative of binding energy with duster size show that besides N = 8, N =11 is also a magic number. Furthermore, it is the first time to find that the ground state of 11-atom clusters is a biplanar structure as same as the 13-atom cluster. The clear odd-even alternation as cluster size for the formation energy indicates the stability of electronic close shell existed in the range studied.展开更多
Measurements of gaseous pollutants （03, NOx, SO2, and CO） were conducted at Dinghushan background station in southern China from January to December 2013. The levels and variations of O3, NOx, SO2, and CO were analy...Measurements of gaseous pollutants （03, NOx, SO2, and CO） were conducted at Dinghushan background station in southern China from January to December 2013. The levels and variations of O3, NOx, SO2, and CO were analyzed and their possible causes discussed. The annual average concentrations of 03, NOx, SO2, and CO were 24.6 ± 23.9, 12.8 ± 10.2, 4.0 ± 4.8, and 348 ± 185 ppbv, respectively. The observed levels of the gaseous pollutants are comparable to those at other background sites in China. The most obvious diurnal variation of 03 was observed in autumn, with minima in the early morning and maxima in the afternoon. The diurnal variations of SO2 showed high values during the day. The diurnal cycles of NOx showed higher values in the morning and lower values during the night. Higher CO concentrations were observed in spring followed by winter, autumn, and summer. Biomass burning, in combination with the transport of regional pollution, is an important source of CO, SO2, and NOx in spring and winter. Backward trajectories were calculated and analyzed together with corresponding pollutant concentrations. The results indicate that air masses passing over polluted areas are responsible for the high concentrations of gaseous pollutants at the Dinghushan background station.展开更多
文摘A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copper clusters. Our results show that the three-dimensional isomers of copper clusters start from Cu7 cluster and then show a tendency to form more compact structures. The results of the formation energy and the second derivative of binding energy with duster size show that besides N = 8, N =11 is also a magic number. Furthermore, it is the first time to find that the ground state of 11-atom clusters is a biplanar structure as same as the 13-atom cluster. The clear odd-even alternation as cluster size for the formation energy indicates the stability of electronic close shell existed in the range studied.
基金supported by Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA05100100)
文摘Measurements of gaseous pollutants （03, NOx, SO2, and CO） were conducted at Dinghushan background station in southern China from January to December 2013. The levels and variations of O3, NOx, SO2, and CO were analyzed and their possible causes discussed. The annual average concentrations of 03, NOx, SO2, and CO were 24.6 ± 23.9, 12.8 ± 10.2, 4.0 ± 4.8, and 348 ± 185 ppbv, respectively. The observed levels of the gaseous pollutants are comparable to those at other background sites in China. The most obvious diurnal variation of 03 was observed in autumn, with minima in the early morning and maxima in the afternoon. The diurnal variations of SO2 showed high values during the day. The diurnal cycles of NOx showed higher values in the morning and lower values during the night. Higher CO concentrations were observed in spring followed by winter, autumn, and summer. Biomass burning, in combination with the transport of regional pollution, is an important source of CO, SO2, and NOx in spring and winter. Backward trajectories were calculated and analyzed together with corresponding pollutant concentrations. The results indicate that air masses passing over polluted areas are responsible for the high concentrations of gaseous pollutants at the Dinghushan background station.
