Ionic-Liquid-Gating Induced Protonation and Superconductivity in FeSe,FeSe_(0.93)S_(0.07), ZrNCl, 1T-TaS_2 and Bi_2Se_3

We report protonation in several compounds by an ionic-liquid-gating method, under optimized gating conditions.This leads to single superconducting phases for several compounds. Non-volatility of protons allows post-gating magnetization and transport measurements. The superconducting transition temperature T_c is enhanced to 43.5 K for FeSe_(0.93)S_(0.07), and 41 K for Fe Se after protonation. Superconducting transitions with T_c～15 K for ZrNCl,～7.2 K for 1-TaS_2, and ～3.8 K for Bi_2Se_3 are induced after protonation. Electric transport in protonated FeSe_(0.93)S_(0.07) confirms high-temperature superconductivity. Our~1 H nuclear magnetic resonance(NMR)measurements on protonated Fe Se_(1-x)S_x reveal enhanced spin-lattice relaxation rate 1/~1T_1 with increasing x,which is consistent with the LDA calculations that H~+ is located in the interstitial sites close to the anions.     

超高效液相色谱-四级杆静电场轨道阱质谱法快速鉴定鬼针草化学成分

利用超高效液相色谱-四级杆静电场轨道阱质谱联用技术对鬼针草的化学成分进行快速鉴定。采用Hypersil GOLD C₁₈(100 mm×2.1 mm,1.9μm)色谱柱，以乙腈-0.1%甲酸水溶液为流动相进行梯度洗脱，在加热电喷雾离子源(HESI)正负离子模式下对样品进行数据采集。采用高分辨质谱数据，结合对照品、文献、在线数据库，从鬼针草中鉴定出28种成分，包括10种黄酮类成分，6种氨基酸类成分，10种有机酸类成分，2种其它成分，其中壬二酸、7-羟基香豆素、没食子酸3种成分为首次在鬼针草中发现。该研究可为鬼针草的快速鉴定、质量控制方法建立和药效基础研究提供参考。     

Recent progress on magnetic-field studies on quantum-spin-liquid candidates

Quantum spin liquids(QSLs) represent a novel state of matter in which quantum fluctuations prevent the conventional magnetic order from being established, and the spins remain disordered even at zero temperature. There have been many theoretical developments proposing various QSL states. On the other hand, experimental movement was relatively slow largely due to limitations on the candidate materials and difficulties in the measurements. In recent years, the experimental progress has been accelerated. In this topical review, we give a brief summary of experiments on the QSL candidates under magnetic fields. We arrange our discussions by two categories: i) Geometrically-frustrated systems, including triangularlattice compounds YbMgGaO_4 and YbZnGaO_4, κ-(BEDT-TTF)_2 Cu_2(CN)_3, and EtMe_3 Sb[Pd(dmit)_2]_2, and the kagom′e system ZnCu_3(OH)_6 Cl_2; ii) the Kitaev material α-RuCl_3. Among these, we will pay special attention to α-RuCl_3, which has been intensively studied by ours and other groups recently. We will present evidence that both supports and rejects the QSL ground state for these materials, based on which we give several perspectives to stimulate further research activities.     

乙醛酸的微分脉冲极谱法定量分析

建立了乙醛酸的微分脉冲极谱定量分析方法, 乙醛酸在100 g/L KOH底液中, 于-1.35 V (vs. Ag/AgCl)处出现一良好的微分脉冲极谱峰, 并能排除主要杂质草酸的干扰. 乙醛酸浓度与其电流峰幅值呈显著的线性关系, 当标准加入的极谱电流峰高和样品极谱电流峰基本一致时, 测量误差小于0.5%.     

2种添加剂在电有机合成中的应用

通过电解实验分别考察了5个阴极电还原反应和1个阳极电氧化反应在加入添加剂前后电流效率和转化率的变化。所选择的6个反应可以分为2类,一类是原料以分子形式存在于电解液中的反应,另一类是原料以离子形式存在于电解液中的反应。实验间二硝基苯电还原制间苯二胺,3-甲基吡啶氧化制烟酸和邻硝基酚电还原制邻氨基酚(酸性条件下)属于前一类反应,加入添加剂后,它们的电流效率分别由原来的65.69%、28.00%和45.09%变为66.15%、28.45%和37.07%,说明添加剂对原料以分子形式存在的反应没有作用或有抑制作用。实验邻硝基酚电还原制邻氨基酚(碱性条件下),丁二酸的电解全盛和水杨酸电还原制水杨醛属于后一类反应,加入添加剂后,它们的电流效率分别从原来的49.37%、65.06%和24.55%提高到75.80%、78.60%和30.06%,说明添加剂能够提高原料以离子形态存在的反应的电流效率。     

Evidence for Magnetic Fractional Excitations in a Kitaev Quantum-Spin-Liquid Candidate α-RuCl3

It is known that α-Ru Cl₃ has been studied extensively because of its proximity to the Kitaev quantum-spin-liquid（QSL） phase and the possibility of approaching it by tuning the competing interactions. Here we present the first polarized inelastic neutron scattering study on α-Ru Cl₃ single crystals to explore the scattering continuum around the Γ point at the Brillouin zone center, which was hypothesized to be resulting from the Kitaev QSL state but without concrete evidenc...