Advances in Selective Ethylene Oligomerization Based on [PNP]-Ligand Chromium Catalysts

乙烯选择性三聚和四聚催化反应为制备1-己烯和1-辛烯提供了重要途径.在报道和披露的众多结构和组成的催化剂体系中,我们选择[PnP]配位骨架的铬催化剂体系,对其发展和应用进行了综述.论文以结构与催化性能的关联性为主线,阐述[PnP]骨架以及n和P上取代基的电子和立体空间效应对催化性能的影响.从目前的研究态势来看,[PnP]配位骨架的铬催化剂体系在乙烯选择性齐聚生产1-辛烯等线性α-烯烃方面具有发展潜力.The catalytic reaction for the selective ethylene trimerization and tetramerization provides a vital route to the production of 1-hexene and 1-octene.Among the numerous catalysts reported with diverse structures and compositions, we select the [PNP]-ligand based chromium catalysts and focus on illustration on their development and application.This contribution includes seven sections as ethylene(selective) oligomerization catalyst systems, [PNP]-ligand based Cr catalyst system, catalytic mechanism, ethylene oligomerization method, catalytic property, and conclusion and prospect, which will cover almost all of the [PNP]-ligand based Cr catalysts so far studied.In this article, we will mainly discuss the influence on the catalytic property owing to the electronic and/or steric characters of the skeleton as well as the substituents at both N and P atoms of the [PNP]-ligands.In view of the current advances in this field, this [PNP]-ligand based Cr catalyst system is of potencial in application for the production of LAO mainly as 1-octene.聚烯烃催化技术重点实验室基金(No.12DZ2260400); 国家自然科学基金(No.21473142); 教育部创新团队(No.IRT_14R31)资助项目~

Ar的类氦和类锂离子与Mo表面相互作用过程中的x射线发射

在兰州重离子加速器国家实验室电子回旋共振离子源上用Si(Li)探测器观测到了不同动能的Ar15+和Ar16+离子与Mo表面相互作用过程产生的x射线.在不同动能的Ar16+与Mo表面作用过程中不仅能观测到Ar的K层x射线而且能观测到Mo的L层x射线.在不同动能的Ar15+入射下只能观测到Mo的L层x射线.实验结果表明,Ar的K层x射线的产额与入射离子的动能、作用过程中形成的空心原子携带的势能以及入射离子和靶原子x射线的竞争等有关,Mo的L层x射线随入射离子动能的增加而增加

高电荷态离子Ar~(13+)轰击Mo金属表面形成靶原子X射线谱测量

本工作实验研究低能高电荷态Ar13+离子与金属Mo表面作用过程中Mo原子受激发射X射线和X射线强度随入射能量的变化。实验结果表明,低速高电荷离子与金属表面原子相互作用可有效地激发靶原子或靶离子内壳层电子而发射X射线

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel