The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculati...The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13＋ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.展开更多
Geometric and electronic properties of Pdn–1Pb and Pdn （n≤8） clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic c...Geometric and electronic properties of Pdn–1Pb and Pdn （n≤8） clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic clusters. The average bond length of Pdn–1Pb （n≤8） bimetallic clusters is longer than that of pure palladium clusters except for n = 2 and 3. The most stable structure of Pdn–1Pb （n≤7） is the singlet where there is at least a Pd or Pb atom on its excited state. The energy gaps of Pd–Pb binary clusters are narrower than those of Pdn clusters, and then the chemical activity is strengthened when Pdn clusters are doped with Pb.展开更多
The contents of As,Cd,Hg and Pb in 27 Chinese medicinal herbs were determined by ICP-MS with microwave assisted digestion.Cluster analysis was applied to study the distribution characteristics of As,Cd,Hg and Pb in di...The contents of As,Cd,Hg and Pb in 27 Chinese medicinal herbs were determined by ICP-MS with microwave assisted digestion.Cluster analysis was applied to study the distribution characteristics of As,Cd,Hg and Pb in different kinds of Chinese medical herbs from different sources.The result of cluster analysis showed that the contents of As,Cd,Hg and Pb from different sources were significantly different.It is helpful in the quality control and source identification of Chinese medicinal herbs.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.20773047 and 21043001)
文摘The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13＋ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.
文摘Geometric and electronic properties of Pdn–1Pb and Pdn （n≤8） clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic clusters. The average bond length of Pdn–1Pb （n≤8） bimetallic clusters is longer than that of pure palladium clusters except for n = 2 and 3. The most stable structure of Pdn–1Pb （n≤7） is the singlet where there is at least a Pd or Pb atom on its excited state. The energy gaps of Pd–Pb binary clusters are narrower than those of Pdn clusters, and then the chemical activity is strengthened when Pdn clusters are doped with Pb.
文摘The contents of As,Cd,Hg and Pb in 27 Chinese medicinal herbs were determined by ICP-MS with microwave assisted digestion.Cluster analysis was applied to study the distribution characteristics of As,Cd,Hg and Pb in different kinds of Chinese medical herbs from different sources.The result of cluster analysis showed that the contents of As,Cd,Hg and Pb from different sources were significantly different.It is helpful in the quality control and source identification of Chinese medicinal herbs.
