Xe对NO(X)微分截面和非弹性散射中的碰撞诱导旋转准直

本文对NO(X)-Xe碰撞系统在碰撞能量为519 cm^-1,测量了完全?-双峰分解的微分截面和碰撞引起的旋转准直力矩. 同时结合初始量子态选择,使用六极杆的非均质电场,借助量子态分辨的测量,利用(1+1'')共振增强的多光子电离和速度离子成像. 结果显示,微分截面以及偏振相关的微分截面均显示与从头算势能面上进行的量子力学散射计算[J. K?os etal. J. Chem. Phys. 137, 014312 (2012)]一致. 通过与准经典轨迹、硬壳势能的量子力学散射以及运动近端模型的比较,评估了势能对所测微分截面和碰撞引起的旋转准直力矩的影响.     

Co(η(5) -P(5) ){η(2) -P(2) H(mes)}](2-) : A Phospha-Organometallic Complex Obtained by the Transition-Metal-Mediated Activation of the Heptaphosphide Trianion

A carbon copy: The chemical activation of the heptaphosphide trianion with [Co(PEt(2) Ph)(2) (mes)(2) ] (see picture; 1) yields the novel phospha-organometallic complex [Co(η(5) -P(5) ){η(2) -P(2) H(mes)}](2-) (2). The reaction product maintains the nuclearity of the parent cluster, but extensive cage fragmentation takes place to yield a diamagnetic "inorganometallic" cobalt complex.     

Continuous‐Flow Electrochemical Generator of Hypervalent Iodine Reagents: Synthetic Applications

An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed. In the anodic oxidation of iodoarenes to hypervalent iodine reagents under flow conditions, the use of electricity replaces hazardous and costly chemical oxidants. Unstable hypervalent iodine reagents can be prepared easily and coupled with different substrates to achieve oxidative transformations in high yields. The unstable, electrochemically generated reagents can also easily be transformed into classic bench‐stable hypervalent iodine reagents through ligand exchange. The combination of electrochemical and flow‐chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches.     

Flow electrochemistry: a safe tool for fluorine chemistry

The heightened activity of compounds containing fluorine, especially in the field of pharmaceuticals, provides major impetus for the development of new fluorination procedures. A scalable, versatile, and safe electrochemical fluorination protocol is conferred. The strategy proceeds through a transient (difluoroiodo)arene, generated by anodic oxidation of an iodoarene mediator. Even the isolation of iodine(iii) difluorides was facile since electrolysis was performed in the absence of other reagents. A broad range of hypervalent iodine mediated reactions were achieved in high yields by coupling the electrolysis step with downstream reactions in flow, surpassing limitations of batch chemistry. (Difluoroiodo)arenes are toxic and suffer from chemical instability, so the uninterrupted generation and immediate use in flow is highly advantageous. High flow rates facilitated productivities of up to 834 mg h⁻¹ with vastly reduced reaction times. Integration into a fully automated machine and in-line quenching was key in reducing the hazards surrounding the use of hydrofluoric acid.

A scalable, efficient and safe electrochemical fluorination protocol is conferred. A broad range of iodine(iii) mediated transformations were performed in high yields without exposure to toxic HF.     

Probing Degradation in Lithium Ion Batteries with On-Chip Electrochemistry Mass Spectrometry**

The rapid uptake of lithium ion batteries (LIBs) for large scale electric vehicle and energy storage applications requires a deeper understanding of the degradation mechanisms. Capacity fade is due to the complex interplay between phase transitions, electrolyte decomposition and transition metal dissolution; many of these poorly understood parasitic reactions evolve gases as a side product. Here we present an on-chip electrochemistry mass spectrometry method that enables ultra-sensitive, fully quantified and time resolved detection of volatile species evolving from an operating LIB. The technique's electrochemical performance and mass transport is described by a finite element model and then experimentally used to demonstrate the variety of new insights into LIB performance. We show the versatility of the technique, including (a) observation of oxygen evolving from a LiNiMnCoO₂ cathode and (b) the solid electrolyte interphase formation reaction on graphite in a variety of electrolytes, enabling the deconvolution of lithium inventory loss (c) the first direct evidence, by virtue of the improved time resolution of our technique, that carbon dioxide reduction to ethylene takes place in a lithium ion battery. The emerging insight will guide and validate battery lifetime models, as well as inform the design of longer lasting batteries.     

Electronic basis of visible region activity in high area Sn-doped rutile TiO2 photocatalysts

The influence of Sn doping on the anatase-to-rutile phase transition has been investigated in high area powders prepared by a sol-gel route involving alkoxide precursors. Sn doping facilitates conversion of anatase to rutile at lower temperatures than observed for undoped material. At the same time Sn-doping inhibits sintering as gauged by line widths in X-ray diffraction and gas-adsorption surface area measurements. These observations are linked to the finding of pronounced segregation of Sn to the surface of rutile TiO(2) observed in X-ray photoemission spectra. Sn-doped TiO(2) is found to exhibit enhanced visible region photocatalytic activity as compared with undoped material in dye degradation experiments. This is attributed to narrowing of the bulk bandgap at low doping levels coupled with the introduction of surface states associated with segregated Sn ions in the divalent state. The Sn(II) surface states lie above the top of the main valence band and can therefore act as trapping sites for holes produced under photoexcitation.     

Differential Cross Sections and Collision-Induced Rotational Alignment in Inelastic Scattering of NO(X) by Xe

Fully \begin{document}$ \Lambda $\end{document}-doublet resolved differential cross sections and collision-induced rotational alignment moments have been measured for the NO(X)–Xe collision system at a collision energy of 519 cm\begin{document}$ ^{-1} $\end{document}. The experiments combine initial quantum state selection, employing a hexapole inhomogeneous electric field, with quantum state resolved detection, using (1+1\begin{document}$ ' $\end{document}) resonantly enhanced multiphoton ionization and velocity map ion imaging. The differential cross sections and polarization dependent differential cross sections are shown to agree well with quantum mechanical scattering calculations performed on ab initio potential energy surfaces [J. K?os et al. J. Chem. Phys. 137 , 014312 (2012)]. By comparison with quasi-classical trajectory calculations, quantum mechanical scattering calculations on a hard-shell potential, and kinematic apse model calculations, the effects of the attractive part of the potential on the measured differential cross sections and collision-induced rotational alignment moments are assessed.     

Sequential Photochemical and Prins Reactions for the Diastereoselective Synthesis of Tricyclic Scaffolds

Cyclobutene alcohols undergo Prins cyclisations to generate single diastereomers of novel tricyclic heterocycles with five contiguous stereocentres. The reaction times are significantly shorter (ca. 15 min) than with traditional alkene substrates. Stereoselective aza‐Prins cyclisations of cyclobutene amine derivatives give fused aza‐heterocyclic scaffolds. Computational studies provide insight into the observed stereocontrol. The modular approach is flexible, enabling the introduction of a variety of functional groups (including amides, nitriles, alkynes, and arenes) into the sp³‐rich heterocyclic scaffolds.